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olegt



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Joined: Dec. 2006

(Permalink) Posted: June 09 2011,10:40   

As promised, Casey takes up the defense of Sewell's argument from the second law. Behold! Digging Into Granville Sewell's Peer-Reviewed Paper Challenging Darwinian Evolution.

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As I noted in a previous article, many have argued that the second law of thermodynamics is not a valid argument against Darwinian evolution since the law holds that order can increase in an open system, and the earth and its biosphere do not comprise a closed system. While that is correct, Granville Sewell, author of In the Beginning: And Other Essays on Intelligent Design, argues there is more to the story. Sewell's article written for Applied Mathematics Letters argues that the second law of thermodynamics may be a problem for Darwinian evolution after all.


Casey makes some statements distancing himself from the second-law argument:

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Now I am not personally convinced that the second law of thermodynamics is the right way to challenge neo-Darwinian evolution, and I prefer Dembski's formulation. But I think that Sewell's article makes interesting points that contribute to this discussion, and it certainly did not deserve to be withdrawn just because some Darwin lobbyists didn't like its conclusion.


He defends Sewell nonetheless. (Why would a tenured professor of applied math need defending by a lawyer whose knowledge of physics ended with Physics 102?) Anyway, Casey does not advance any new arguments, just quotes a few passages from Sewell's manuscript. Here is the gist of it (emphasis mine):

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Sewell observes that materialists claim that a reduction in entropy in a part of the universe can occur if it is compensated by an increase in another part. As he quotes Peter Urone: "it is always possible for the entropy of one part of the universe to decrease, provided the total change in entropy of the universe increases." Sewell then argues that this "compensation" rejoinder fails:
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Of course the whole idea of compensation, whether by distant or nearby events, makes no sense logically: an extremely improbable event is not rendered less improbable simply by the occurrence of "compensating" events elsewhere. According to this reasoning, the second law does not prevent scrap metal from reorganizing itself into a computer in one room, as long as two computers in the next room are rusting into scrap metal--and the door is open.



This is totally, completely wrong. It shows that Sewell does not understand thermodynamics. (Neither does Luskin, but that is hardly a surprise.)

Here is a simple counter example. Pour a glass of water and drop a cube of ice into it. The water will get colder. The motion of water molecules will slow down and its entropy will decrease. We can even calculate by how much. Suppose the temperature of water drops by 1 degree centigrade. 200 g of water gives off about Q = 0.8 joules of heat. That flow of heat takes away entropy S_w = -Q/T_w, where T_w is the absolute temperature of water. Let's say it is 27 degrees centigrade, or 300 K. Let's also convert the entropy to bits by dividing it by the Boltzmann constant k and the natural logarithm of 2:

S_w = -Q/(kT ln(2)) = -2.9 x 10^20 bits.

This is an enormously large decrease in entropy. The probability of that happening spontaneously is 2 to the power S_w, roughly one in 10^(88 000 000 000 000 000 000). This is very, very improbable. What gives?

Of course, the decrease in the entropy of water is more than compensated by an increase in the entropy of ice. Ice receives the same amount of heat but does so at a lower temperature T_i, 0 centigrade, or 273 K. Its entropy increase is S_i = +Q/T_i = 3.2 x 10^20 bits.

The total entropy change,

S_w + S_i = Q(1/T_i - 1/T_w) = 3 x 10^19 bits,

is positive because ice is colder than water, T_i < T_w.

So in this example, water goes into an incredibly less probable state as a result of cooling. That probability decrease is compensated, and then some, by the heating of ice. In fact, the full system (water + ice) ends up in a much more probable state as a result of the overcompensation.

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