19. Thermodynamic Law and Self- Organizing Systems
The important consideration of the relationship between thermodynamics and self-organizing systems has been left to the end because thermodynamic laws are so all-pervasive that their existence overshadows all and it provides a opportunity for summing up.
Definitions
The 2nd Law of Thermodynamics
1. In a closed system (one isolated from its environment) the heat flow out of one part of the system cannot be transformed completely into mechanical energy. It is always accompanied by heat flow into a cooler part of the system. Therefore no engine can work at 100% efficiency. There is always a transfer to unusable heat due to conduction and friction.
2. Heat never flows spontaneously from a cooler body to a hotter one.
3. For a closed system the direction of spontaneous change is from order to disorder.
4. The entropy of a closed system always increases or remains the same.
5. The entropy of the universe tends toward a maximum.
Entropy
1. the quantity of heat loss during energy transitions; or, in heat engines, entropy is the amount of heat which cannot be converted into work because it is dispersed into the surroundings.
2. the measure of disorder in a system.
Closed systems - those that are isolated from their environment.
Open systems - those that continuously exchange matter and energy with their environment.
Dissipative structures - systems far from equilibrium which maintain a high degree of organization by dissipating entropy to the environment.
Background
No general discussion of self-organizing systems would be complete without relating that discussion to the 2nd Law of thermodynamics which has been held to be the most primary law of physics.
The world view evoked by the 2nd Law is one in which, in general, things fall apart, everything tends to level out, and disorder increases until all that is left is only the quiet vibrations of molecules. No further change can take place.
A world full of self-organizing systems seems to be in direct contrast. Things tend to become more complex. They build themselves up from simpler structures. They create more order and organization in the world and, as time goes on, more and more special arrangements are achieved.
Discussion
The two views expressed above would seem to be in conflict. Indeed, some science writers have suggested that there are two arrows of time. The first arrow is the general tendency toward entropy increase. Before and after can be distinguished by amount of energy disorganization in a system. Given two pictures - a glass with water on a table and one of pieces of glass on the floor with water spreading out - one can easily say which was taken first.
The suggestion of another arrow of time is based on the observed tendency toward increased organization and complexity. In the beginning there was a primeval structure that produced the big bang, powerful but relatively simple. Today, about 13.7 billion years later, there are multitudes of physical structures from atoms and molecules to astronomical objects of bewildering variety. Highly organized patterns of chemical, biological, and cultural systems have evolved. Along with the increase in numbers of structures comes an increasingly complex web of interrelationships.
Thus, our universe seems to have two large scale tendencies: one destructive and inevitable the leveling out of things; the other constructive and equally inevitable the organization of things. The universe is steadily running downhill in the sense of the disbursing of its energy, while at the same time parts of it are running uphill in the sense of building structure through self-organization.
We know what the final end is likely to be but self organization spreads a lovely light.
Can the growth of structure and organization be reconciled with the 2nd Law?
An important characteristic of self-organizing systems is that they are open systems; systems which give and receive matter and energy to and from their environment.
Traditional physics and chemistry study closed systems where the 2nd Law is easily applied. To resolve the difference in perspective between that of the 2nd Law with that of self-organizing systems a new approach was needed. A leading figure in the development of what has begun to be called non-equilibrium thermodynamics was Ilya Prigogine of the Free University of Brussels. For his work relating to chemical systems far from equilibrium he was awarded the Nobel Prize in Chemistry in 1977.
Prigogine coined the term dissipative structures to describe those systems which display a high degree of organization through the exchange of matter and energy with their environment. In choosing this phrase he wanted to emphasize the constructive role of dissipative processes in their formation. Dissipative structures maintain themselves only as long as some form of work is done on them. They spontaneously self-organize when conditions permit and reflect the interaction of a given system with its surroundings.
If the flow of matter and energy to a dissipative structure ceases its organization disappears. An essential feature of dissipative structures is the exportation of the entropy they produce into the environment. The total entropy of the universe therefore increases. What Prigogine has shown is that the spontaneous formation of organized structures is not forbidden by the 2nd Law.
The work of the Brussels School has gone further. The study of non equilibrium processes has shown that dissipative structures are subject to abrupt spontaneous changes of behavior. At certain thresholds of complexity a kind of phase transition may occur, or bifurcations in developmental pathways may present themselves. Which direction the system goes is unpredictable. In this way dissipative structures can reorganize themselves into new and unexpected forms. Prigogine has called this order through fluctuation, and has written, What seems certain is that these farfrom- equilibrium phenomena illustrate an essential and unexpected property of matter.
A revolutionary view of the 2nd Law is being revealed. It is not simply the inexorable arrow pointing toward degeneration and a universal equilibrium where all change ceases. The processes of energy transformation must include the tendency toward the formation of transient organized structures under far from equilibrium conditions which can evolve and produce new structures and behaviors.
Beyond reconciliation, toward partnership
Not only does the 2nd Law permit the evolution of complex systems but the process of structuring is actually promoted by the Law. This is the claim of the late Jeffrey Wicken, professor of science at Behrend College, Pa. Wicken especially focuses on living systems; organisms, populations, and societies. He regards them as patterns of entropy production whose stabilities are maintained by certain purposive internal organizations.
In chemistry Le Chateliers principle expresses the idea that if stress is applied to a system at equilibrium, the system will change in the direction of reducing the stress. A physical example of this is the change of ice to water when pressure is applied. The stress of pressure, even without a change in temperature, forces the system to change. Since the volume occupied by water is less than that of ice the ice system changes in that direction.
Wicken sees the evolutionary process as something like an extension of Le Chateliers principle in that living systems must also adjust to applied forces or energy gradients. Although Le Chateliers principle applies to systems in equilibrium and Wicken is talking about systems far from equilibrium there is the possibility of a synthesis of the ideas.
The total biosphere can be considered to be a system whose equilibrium is being upset by the input of energy. It is continually being bombarded by energy from the Sun. Through the process of photosynthesis there is a conversion to chemical potential energy. This potential energy puts a stress on the biosphere. The stress is relieved by the evolutionary process in its movement from the simple and unorganized to the complex and highly organized.
Natural selection, then, is a consequence of thermodynamic flows through the biosphere. The means of relieving the energy gradient built up by photosynthesis is by the generation of more complex organisms that are, presumably, more energy efficient.
A new species or a new technology that makes more efficient use of this energy flow will likely be favored and will be selectively preserved. All organisms, the biosphere itself, become part of the Earth system which adjusts to the energy input from the Sun by heat radiation out into space. Thus there is no incompatibility between the 2nd Law and biological evolution.
In this analysis the tendency toward the dissipation of energy is the source of the development of complex organisms. Life is not an accident due to the chance aggregation of molecules. It is a natural outcome of the flow of energy or, as Wicken puts it, a necessary consequence of thermodynamic laws.