Why is life? An assessment of the thermodynamic properties of dissipative, pattern-forming systems

摘要

This document charts a series of investigations into some basic questions concerning the relationship between life and the physical theories of thermodynamics. While equilibrium thermodynamics represents a foundational component of modern physics, methods for non equilibrium systems have yet to reach the same level of maturity. The first part of this thesis aims to establish the validity of a burgeoning theory of non-equilibrium thermodynamics known as the Maximum Entropy Production Principle (MEPP), in the context of heat transfer by convective fluid motion between heated boundaries. Applying the MEPP to systems with both fixed and negative feedback boundary conditions revealed that in fact, the steady state of convective fluids cannot be accurately predicted from an assumption of maximum entropy production alone. Rather the subtleties of the boundary conditions and the physical properties of the fluid must be properly accounted for. It is thus proposed that the MEPP should not, as has sometimes been suggested, be treated as a universally applicable law of nature. The second part of this thesis investigates the pattern-forming and transport properties of reactive fluid systems. It is found that under thermal driving forces, closed systems utilise the physical processes of reaction and advection to augment their heat transport abilities. Furthermore, the addition of thermal kinetics and fluid flow to the Gray-Scott reaction diffusion system, reveals a new range of phenomena including positive feedback, self-inhibition, competition and symbiosis. Such behaviour can readily be viewed from an ecological, rather than purely physico-chemical, perspective.