Prigogine Investigation Essay Example for Free

Prigogine Investigation Essay The origination and evolution of living organisms is considered by many scientists, due to general laws of nature, especially the second law of thermodynamics. In this paper this idea is explored, taking in account the dissipative structures and Prigogine’s thermodynamics. Introduction The use of thermodynamics in biology has a long history rich in confusion (Morowitz, 92) (Klyce, Brigg, http://www. panspermia. org/seconlaw. htm) The second law of thermodynamics was discovered by Clausius, who coined the term Entropy, which is usually defined as the degree of disorder. In the most general sense, Evolution of life means, growing in ordered combinations from cells, to tissues and organs, to plants and animals, families, communities, and ecosystem. It can be seen that these two terms: evolution and entropy express totally contradictory concepts. According to second law, Entropy of a closed system can never decrease, i. e. dSV ? 0 (Gibbs, 1928). But, in case of evolution, the living systems increasingly go on to complex state of more order, suggesting that entropy in this closed system has decreased. This is the paradox that has baffled both biologists and physicists alike. Hence, an initial theory which both physicists and biologists agreed upon was: life violates the second law of thermodynamics. Evolution of life and Entropy The contradiction can however be explained, by subscribing to one of the two very different schools of thought. Either we can accept that the order that is seen in the evolution and growth biological systems is maintained at the expense of thermodynamic order. That is to say, sustenance in the form of external energy is always provided to the organism from external environment and entropy of this larger system is increasing. Hence, living beings attract negative entropy, in order to compensate for this increase in the entropy, which explains the order. This concept was formed by Schrodinger. There is another explanation, which was proposed by Prof. Ilya Prigogine. According to him, the living organisms function as dissipative structures, i. e. thermodynamically open systems operating in non-equilibrium environment. These have the capacity for self-organization in the face of environmental fluctuations. In other words, they maintain their structure by continuously dissipating energy. Such dissipative structures are permanently in states of non-equilibrium. Ds/dt 0 away from steady state Ds/dt = 0 steady state (Prigogine, 1977) In this case, equilibrium is the state of maximum entropy. A system that is not in equilibrium exhibits a variation of entropy, which is the sum of the variations of entropy due to the internal source of entropy, plus the variation of entropy due to the interaction with the external world. The former is positive, but the latter can be negative. Therefore, total entropy of the system can decrease. Life according to this theory can then be summarized as: An organism lives because it absorbs energy from the external world and processes it to generate an internal state of lower entropy. It can live as long as it can avoid falling in the equilibrium state. According to the second law, only irreversible processes contribute to entropy production. This means the existence of a function in an isolated system which can only increase in time. It follows that the positive time direction is associated with entropy (Prigogine, 1977). Now, biological evolution is hierarchical and can be considered as an irreversible process of the variation of life with respect to the evolutionary time scale. The Law of Temporal Hierarchies makes it possible to identify quasi-closed thermodynamic systems and subsystems within open biological systems (Gladyshev, 2003). This facilitates the study of individual development (ontogenesis) and evolution (phylogenesis) of these subsystems. For instance, it is seen that the specific Gibbs function for the formation of supramolecular structures of biological tissues, G tends towards its minimum in the course of both ontogenesis and phylogenesis. (Gladyshev, 2005) The above model implies that, the mean flow of matter is quasi-stationary and the nature of incoming matter to the system remains practically unchanged. In other words, the supramolecular phase (structure) of the organism evolves against the background of the incoming flow of chemical substances of practically constant composition. This principle of the stability of chemical substances is a thermodynamic principle. Accordingly, the tendency of biological systems during evolution to generate relatively highly stable structures of higher hierarchies leads to the selection of relatively less stable structures of lower hierarchies. This rejuvenates the lower hierarchical structures and causes nearly unbounded evolution of the biological world. (Gladyshev, 2005) Conclusion The findings of hierarchical thermodynamics, specifically supramolecular thermodynamics of quasi-closed systems, confirm the thermodynamic tendency of biological evolution. Additional experiments could refine this model and further verify that second law can be applied in its classical definition to explain the origin and evolution of life References 1. Gladyshev, Georgi P. â€Å"What is Life- A physical chemist’s viewpoint†, 12th Dec. 2005 http://www.panspermia.org/seconlaw.htm