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Re: Ecological Economics and Entropy



Jay Hanson has finally given us something to chew on rather than
merely references.

     The two essential forms of stored thermodynamic potential
     are "energy" (e.g., a barrel of oil) and "order" (e.g.,
     clean drinking water and deep topsoil). "Entropy" is a
     measure of the unavailability of energy: the entropy of oil
     increases as it burns, and the entropy of a water table
     increases as it falls because more energy will be required
     to pump it to the surface. Entropy can also be thought of as
     a measure of disorder in a system: polluted water that
     requires purification has higher entropy than the same water
     unpolluted, and the entropy of topsoil increases when it is
     dispersed or polluted by salt from evaporating irrigation
     water.

Thermodynamics only recognizes one entropy, because all of its
manifestations are transformable into one another.  For example, water
that requires purification can be purified (its entropy reduced) by
using free energy from nuclear or solar power (thereby increasing the
entropy of the rest of the universe).  However, neither nuclear nor
solar free energy will run out in the next 5 billion years, so Hanson
needs some additional argument to show that we are doomed in less than
34 years.

-- 
John McCarthy, Computer Science Department, Stanford, CA 94305
http://www-formal.stanford.edu/jmc/progress/
During the last years of the Second Millenium, the Earthmen complained
a lot.


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