+quot;the second law+quot; The second law of thermodynamics is often misquoted eps. in the

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"the second law" The second law of thermodynamics is often misquoted - eps. in the popular press and by physics students - and most especially by creationists. It does NOT say that entropy always increases. It says that in a CLOSED system in THERMAL EQUILIBRIUM, the entropy always increases (or stays the same). Entropy, like temperature, is defined for a system in thermal equilibrium - or at least that's the situation in traditional thermodynamics from which the 3 laws follow. Thermal equilibrium has to do with the way in which energy is partitioned in the system - and a system if left alone will typically tend toward equilibrium. If the system is not in equilibrium, such as the earth, then there isn't a globally well defined entropy, so the second law does not apply (although it does apply to approximately closed subsystems in equilibrium with themselves). Creationists are either uninformed or dishonest if they use entropy arguments against evolution. The earth is not a closed system for one thing, and it isn't in thermal equalib. for another. There is, however, a developing field of non-equalib. thermodynamics that attempts to generalize the concept of entropy (amongst other things). You can define a local entropy density and there are situations in which you can have spontaneous decrease in entropy in one location at the expense of a greater entropy increase in another location. This is the situation of the earth-sun system. Hope this helps. BTW - thermodynamics/statistical mechanics is not a fundamental physical theory. It describes the behavior of matter in bulk if certain conditions are met (i.e. thermal equalim.) bob singleton bobs@thnext.mit.edu


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