Life as a Manifestation of the Second Law of Thermodynamics

We examine the thermodynamic evolution of various evolving systems, from primitive physical systems to complex living systems, and conclude that they involve similar processes which are phenomenological manifestations of the second law of thermodynamics. We take the reformulated second law of thermodynamics of Hatsopoulos and Keenan and Kestin and extend it to nonequilibrium regions, where nonequilibrium is described in terms of gradients maintaining systems at some distance away from equilibrium. The reformulated second law suggests that as systems are moved away from equilibrium they will take advantage of all available means to resist externally applied gradients. When highly ordered complex systems emerge, they develop and grow at the expense of increasing the disorder at higher levels in the system's hierarchy. We note that this behaviour appears universally in physical and chemical systems. We present a paradigm which provides for a thermodynamically consistent explanation of why there is life, including the origin of life, biological growth, the development of ecosystems, and patterns of biological evolution observed in the fossil record. We illustrate the use of this paradigm through a discussion of ecosystem development . We argue that as ecosystems grow and develop, they should increase their total dissipation, develop more complex structures with more energy flow, increase their cycling activity, develop greater diversity and generate more hierarchical levels, all to abet energy degradation. Species which survive in ecosystems are those that funnel energy into their own production and reproduction and contribute to autocatalytic processes which increase the total dissipation of the ecosystem. In short ecosystems develop in ways which systematically increases their ability to degrade the incoming solar energy. We believe that our thermodynamic paradigm makes it possible for the study of ecosystems to be developed from a descriptive science to a predictive science founded on the most basic principle of physics. REFERENCE: Schneider, E.D, Kay, J.J., 1994, "Life as a Manifestation of the Second Law of Thermodynamics", Mathematical and Computer Modelling, Vol 19, No. 6-8, pp.25-48 © James J. Kay and Eric Schneider, 1992 INTRODUCTION In 1943 Erwin Schrödinger (1944) wrote his small book What is Life? , in which he attempted to draw together the fundamental processes of biology and the sciences of physics and chemistry. He noted that life was comprised of two fundamental processes; one "order from order" and the other "order from disorder". He observed that the gene with it's soon to be discovered DNA, controlled a process that generated order from order in a species, that is the progeny inherited the traits of the parent. Schrödinger recognized that this process was controlled by an aperiodic crystal, with unusual stability and coding capabilities. Over a decade later these processes were uncovered by Watson and Crick. Their work provided biology with a framework that allowed for some of the most important findings of the last thirty years. However, Schrödinger's equally important and less understood observation was his "order from disorder" premise. This was an effort to link biology with the fundamental theorems of thermodynamics. He noted that at first glance, living systems seem to defy the second law of thermodynamics as it insists that, within closed systems, entropy should be maximized and disorder should reign. Living systems, however, are the antithesis of such disorder. They display marvelous levels of order created from disorder. For instance, plants are highly ordered structures, which are synthesized from disordered atoms and molecules found in atmospheric gases and soils. Schrödinger solved this dilemma by turning to nonequilibrium thermodynamics, that is he recognized that living systems exist in a world of energy and material fluxes. An organism stays alive in its highly organized state by taking energy from outside itself, from a larger encompassing system, and processing it to produce, within itself, a lower entropy, more organized state. Schrödinger recognized that life is a far from equilibrium system that maintains its local level of organization at the expense of the larger global entropy budget. He proposed that to study living systems from a nonequilibrium perspective would reconcile biological self-organization and thermodynamics. Furthermore he expected that such a study would yield new principles of physics. This paper takes on the task proposed by Schrödinger and expands on his thermodynamic view of life. We explain that the second law of thermodynamics is not an impediment to the understanding of life but rather is necessary for a complete description of living processes. We further expand thermodynamics into the causality of the living process and assert that the second law is a necessary but not sufficient cause for life itself. In short, our reexamination of thermodynamics shows that the second law underlies and determines the direction for many of the processes observed in the development of living systems. This work harmonizes physics and biology at the macro level and shows that biology is not an exception to physics, we have simply misunderstood the rules of physics. Life and the Second Law 2 by Eric Schneider and James Kay Central to our discussion is a fresh look at thermodynamics. Since the time of Boltzmann and Gibbs there have been major advances in thermodynamics especially by Carathéodory, Hatsopoulos and Keenan, Kestin, Jaynes, and Tribus. We take the restated laws of thermodynamics of Hatsopoulos and Keenan and Kestin and extend them so that in nonequilibrium regions processes and systems can be described in terms of gradients maintaining systems away from equilibrium. In this context the second law mandates that as systems are moved away from equilibrium they will take advantage of all means available to them to resist externally applied gradients. Our expansion of the second law immediately applies to complex systems in nonequilibrium settings unlike classical statements which are restricted to equilibrium or near equilibrium conditions. Away from equilibrium, highly ordered stable complex systems can emerge, develop and grow at the expense of more disorder at higher levels in the system's hierarchy. We will demonstrate the utility of these restatements of the second law by considering one of the classic examples of dissipative structures, Bénard Cells. We argue that this paradigm can be applied to physical and chemical systems, and that it allows for a thermodynamically consistent explanation of the development of far from equilibrium complex systems including life. As a case study we focus on the applications of these thermodynamic principles to the science of ecology. We view ecosystems as open thermodynamic systems with a large gradient impressed on them by the sun. The thermodynamic imperative of the restated second law is that these systems will strive to reduce this gradient by all physical and chemical processes available to them. Thus ecosystems will develop structures and functions selected to most effectively dissipate the gradients imposed on them while allowing for the continued existence of the ecosystem. We examine one ecosystem closely and using analyses of carbon flows in stressed and unstressed conditions we show that the unstressed ecosystem has structural and functional attributes that lead to more effective degradation of the energy entrained within the ecosystem. Patterns of ecosystem growth, cycling, trophic structure and efficiencies are explained by this paradigm. A rigorous test of our hypothesis is the measurement of reradiated temperatures from terrestrial ecosystems. We argue that more mature ecosystems should degrade incoming solar radiation into lower quality exergy, that is have lower reradiated temperatures. We then provide data to show that not only are more mature ecosystems better degraders of energy (cooler) but that airborne infrared thermal measurements of terrestrial ecosystems may offer a major breakthrough in providing measures of ecosystem health or integrity. CLASSICAL THERMODYNAMICS Because the basic tenets of this paper are built on the principles of modern thermodynamics, we start this paper with a Life and the Second Law 3 by Eric Schneider and James Kay brief discussion of thermodynamics. We ask the reader who is particularly interested in ecology to bear with us through this discussion, because an understanding of these aspects of thermodynamics will make much of our discussion of ecology self-evident. For the reader who has mastered thermodynamics we believe that our approach to the theoretical issues of nonequilibrium thermodynamics is original and permits a more satisfactory discussion of observed far from equilibrium phenomena. Comparatively speaking, thermodynamics is a young science but has been shown to apply to all work and energy systems including the classic temperature-volume-pressure systems, chemical kinetic systems, electromagnetic and quantum systems. The development of classical thermodynamics was initiated by Carnot in 1824 through his attempts to understand steam engines. He is responsible for the notion of mechanical work, cycles, reversible processes, and early statements of the first and second law. Clausius in the period 1840 to 1860 refined Carnot's work, formalizing the first and second law and the notion of entropy. The first law arose from efforts to understand the relation between heat and work. Most simply stated, the first law says that energy cannot be created or destroyed and that despite the transformations that energy is constantly undergoing in nature (i.e. from heat to work, chemical potential to light), the total energy within a closed or isolated system remains unchanged. It must be remembered that although the total quantity of energy in a closed system will remain unchanged, the quality of the energy in the system (i.e the free energy or the exergy content) may change. The second law requires that if there are any physical or chemical processes underway in a system, then the overall quality of the energy in that system will degrade. The second law of thermodynamics arose from Carnot's experiments with steam engines and his recognition that it was impossible to convert all the heat in such a system completely to work. His formal statement of the second law may be stated as: It is impossible for any system to undergo a process in which it absorbs heat from a reservoir at a single temperature and converts it completely into mechanical work, while ending at the same state in which it began. The second law notes that work may be dissipated into heat, whereas heat may not be converted entirely into work, thus proving the existence of irreversibility in nature. (This was a novel, paradigm shattering suggestion for its time.) The second law can also be stated in terms of the quantitative measure of irreversibility, entropy. Clausius discovered that for any cyclic process1: