Planetary Evolution

An argument is developed to show that the origin and evolution of the perceptual guidance of movements and the movement enhancement of opportunities to perceive, that is, perception-action cycles, have a direct and deep connection with thermodynamic principles.  The cornerstones of the argument are: (a) maximum entropy production as a physical selection principle (thermodynamic fields will behave in such a fashion as to get to the final state- minimize the field potential or maximize the entropy- at the fastest possible rate given the constraints; (b) the inexorability of order production (order produces entropy is inexorable because order produces entropy faster than disorder); (c) evolution as a global phenomenon (the Earth system at its highest level evolves as a single global entity): and (d) information in Gibson's law-based, specificational sense (invariant relations exist between higher order properties of structured energy distributions and their environmental sources). The progressive emergence of perception-action cycles in the evolution of Earth as a global entity is the lawful product of opportunistic physics: There was no other way to produce the collective order (ordered) states that would engender these higher levels of dissipation.  Perception-action cycles express higher order symmetries of the world itself in its own becoming.  Perception-action is the physics at these higher levels.

Selection is entailed by self-organization and a direct consequence of entropy production maximization (LMEP) and natural selection is a special case.  The origin and evolution of life is seen to be a direct consequence of universal physical law.

At a planetary scale the Earth evolves as a single planetary system for which the origin and maintenance of planetary O2 at  relatively constant level is prima facie evidence.  But for orthodox evolutionary theory, namely evolution explained by natural selection this has presented on impossible problem since natural selection works on a population of replicating entities and there is no population of Earth systems on which natural selection can act; the Earth evolves as a population of one ("The Problem of the Population of One").  The problem is obviated and dissolved when it is shown that biological evolution is a particular case of general or physical evolution which can be shown to follow directly, with an expansion of thermodynamics from physical law.

The 238U/204Pb ratio of the Earth's mantle is conventionally seen as reflecting the loss of lead to the Earth's core, implying that this element is siderophile. A contrasting view holds that lead may be depleted because it did not fully condense at the accretion temperatures of the early Earth. Experiments reported here show that lead is indeed quite siderophile at high temperature. At the same time, it is noted that no plausible set of physical conditions exists where the present-day abundances of all moderately volatile elements of the mantle could have been in chemical equilibrium with a metallic iron melt. It is argued that a large proportion of the moderately volatile elements, including Pb, were added late, during the waning stages of core formation. In consequence, caution is advised in using the 238U/204Pb and the Pb isotope ratios of the mantle to date the differentiation of the Earth in silicate mantle and metallic core (Hofmann, 2001).