New Criticals

...so anyway, let me remind you what I’ve been trying to show: non-equilibrium thermodynamics teaches us that the emergence of life required at least three critical conditions be met on the early earth. First was a source of concentrated chemical potential energy. The ultimate energy source for all life processes today is, of course, the sun. There’s mounting evidence, however, that the energy sources for the emergence of life were geothermal vents at the bottom of the ocean. Whatever future investigations ultimately decide, it remains the fact that the emergence of life is physically inconceivable apart from some energetic source. Equally necessary is a sink to receive heat dissipated from irreversible, entropy-producing chemical processes. This is the role of water in biochemistry, and the role of outer space for the earth as a whole. Given source-sink conditions, energy flow becomes a physical necessity. Whenever you see large numbers of particles moving spontaneously in concert, such as in the flow of water downhill, you can be certain that energy dissipation is the cause.

The third condition required for the emergence of life is the molecular complexity required to create chemical cycles capable of turning energy flow into organization. Again, if it is possible to increase the heterogeneity of matter in a system, this will always be entropically favorable to some extent because it well increase the number of accessible microstates and thus increase entropy. So for a closed system containing a set of molecules capable of undergoing chemical transformations and subject to persistent energy flux from a source to a sink, it is physically necessary that the diversity of molecules increases up to at least the formation of the first chemical cycles.