Monday, March 12, 2007

Thermodynamics, Entropy and Evolution

I have read several arguments attempting to prove that the tendency for entropy to increase does not contradict the theory of evolution. It seems that in general these arguments are restricted to the second law of themodynamics which is one manifiestation of entropy. The argument goes something like this: Since the sun adds energy to earth, earth is not a thermodynamically closed system. A system consisting of the sun and earth combined is (or approximates) a thermodynamically closed system and its entropy increases, even as the entropy of the earth decreases, thus allowing evolution.

And I want to acknowlege that if you think of entropy only in terms of its thermodynamic properties, the argument seems reasonable. But what I want to make clear is that entropy also applies to the order of a system and information within a system -- such as DNA. And the sun does not add information to the earth's system -- it only adds energy.

One argument that I read suggested that entropy only applies to thermodynamics and that it is not related to order or disorder at all. He then went on to state that there is only one mathematical equation connecting entropy to disorder, namely,

S = k ln W

which is a statistical dynamical description of entropy. Only one mathematical equation -- hmmm. Wait just a minute here -- it's not like we just found a skullcap, a femur, and three teeth and managed through wild conjecture to construct Java man. This is a mathematical equation and you can't discount it because there is only one. Having a Masters degrees in Applied Mathematics I feel a little offended by this attitude (wink).

As a side note S = K ln W is not the only mathematical equation connecting entropy to disorder. Shannon and others have developed several mathematical models to describe entropy in terms of order and information.


At 3:02 PM, February 24, 2008, Anonymous Douglas said...

From about half-way down the Wikipedia page you linked to, there is this comment:

"For example, adding heat to a system increases its thermodynamic entropy because it increases the number of possible microscopic states that it could be in, thus making any complete state description longer."

The "complete state description" is the information held by the system, so by heating a system you are adding information, which resolves your paradox.

At 6:26 PM, March 06, 2008, Blogger Intelligent Designer said...

The complete state description is the information about the system, not the information held by the system.

It sounds like you think that entropy = information. If so you are confused. See the external links at the botton of the Wikipedia page on information entropy. If that doesn't help go boil a pot of water and check for new information (wink).


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