Entropy and Evolution

Many creationists have stated that evolution, since it creates order from disorder, violates the Second Law of Thermodynamics and therefore evolution can not be a correct explanation. Unfortunately, this is but half the story.

The three Laws of Thermodynamics along with the Laws of the Conservation of Angular and Linear Momentum (taking into account the Equivalence of Mass and Energy) are the best established laws of science; no processes including black hole accretion have ever been shown to violate them. If Evolution can properly be shown to violate the Second Law, it is wrong.

The Entropy Change of Heat Flow

The Second Law was first proposed to explain in quantitative terms why heat always spontaneously flows down a temperature gradient. The Second Law is always applied to closed systems, i.e., a system that has no exchange of energy or mass or work with the outside system (or universe). A two compartment system, isolated from the universe, is depicted below for the simple process of transferring heat (q) from System1 to System2:

Universe

System1 Temperature = T1 Heat transferred out = q Entropy loss = S1 = -q/T1

System2 Temperature = T2 Heat transferred in = q Entropy gain = S2 = q/T2

Total Entropy Change (Gain + Loss) = S2+S1 = (q/T2 - q/T1) = (q(T1-T2)T1T2)

Since T1 > T2 the Total Entropy Change is always positive for any spontaneous heat transfer agreeing with the Second Law.

Other Entropy Expressions

The Total Entropy Change of a process can be expressed in other variables than temperature, such as, work, pressure, volume, probability, potential complexity and information content. While some of these representations are rigorous, others are not and the validity of any conclusion based on them is questionable. Anyone trying to deny the validity of a well-established theory needs to be sure their use of entropy is sound and the necessary assumptions are fulfilled. Usually they are not and cannot be fulfilled. These uses will not be pursued here. However, they all involve the entropy changes in at least two systems and the creationists have not accounted for this properly.

Conclusion

It is important to note that it is necessary to consider the entropy gain or loss in both systems 1 and 2 in computing the Total Entropy Change for this simple process before the Second Law can be applied. This is a requirement for ALL applications of the Second Law to any process even when the entropy change is related to changes in order, complexity or probability. This is where the creationists make their first error: they neglect that the Universe is undergoing large changes in entropy as energy and moderately complex organisms are consumed to make evolution possible. In addition, if the creationists were correct, life could not exist as it requires vast quantities of energy and order to continue, reproduce and grow; it's called food.

Given the above error, any other errors in the use of entropy pale by comparison.

More: The following URLs have more information about the Evolution and Entropy controversy as well as other evolution controversies.

Author's Note: It is not surprising that the Second Law application to evolution should result in misapplication and controversy. The Second Law was more controversial than the First Law when it was proposed and has had a very wide range of subtle applications. The extensions by Boltzman and Gibbs were into areas obscure to many scientists and involved some subtle assumptions. It has been tempting to use the Second Law under improper circumstances.