Science in Christian Perspective



One more time...
General Evolution and the Second Law of Thermodynamics
Department of Physics, 
Wheaton College Wheaton, Illinois

The idea that the General Theory of Evolution and the Second Law of Thermodynamics are mutually contradictory is an error based on the failure to recognize that the Second Law allows parts of the universe to decrease entropy (increase order) while requiring that the total amount of disorder in the universe must always increase. Thus the Second Law cannot be used against Evolution, although the distinctly different argument from mathematical improbability is legitimate.


The idea that the Theory of Evolution defies the Second Law of Thermodynamics appears to be making an impression in some circles. I do not know the full history of the idea, but I first encountered it as an excerpt from A. E. Wilder-Smith's book Man's Origin, Man's Destiny1 which was published sometime ago in Christianity Today. That excerpt drew accurate fire from a collection of physicists and engineers who correctly indicated that a complete misunderstanding of the "law" was involved. Despite authoritative criticism, Dr. Wilder-Smith still apparently retains his position.

The Journal ASA 22, 117 (1970) contains a review by a chemist of Wilder-Smith's book. I was disappointed to note that this argument was mentioned with tacit approval. A biologist, in the same issue, also notes the idea with more cautious approval.

I no more concur with the General Theory of Evolution than any of the proponents of this view, but it is a mistake to defend oneself with faulty arguments. I hope to show why this view is faulty. It is then the reader's responsibility to face the truth honestly and act accordingly. There are significant questions of the meaning of theories and laws which could be raised, but the basic issue to which I wish to speak involves the internal consistency of scientific thought. Thus, I shall by-pass some philosophic difficulties and deal only with the central mistake.

Not Technical

The mistake is not at all technical. Ordinarily the Second Law is stated, "The amount of disorder in the universe always increases or remains unchanged for any process." Technically, one substitutes the word "entropy" for "disorder", but the correspondence is sufficiently close that no confusion will result from using "disorder". Also technically, the case where disorder does not change is probably physically unrealizable and certainly it refers to cases (which are of no interest to us) where interacting systems are in equilibrium so that no changes at all take place. Thus, we can state the law, "The amount of disorder in the universe increases for all processes", and be reasonably confident that we are making scientific sense. The error lies in overlooking the absolutely crucial phrase "in the universe". Let me give an example of how crucial this is.

Cooling Water

A warm glass of water can be cooled by placing it in a refrigerator. If you looked only at the water, you would have to conclude that the Second Law had been violated. How so? The agitation of the molecules (which is related to temperature) decreases with decreased temperature. Thus the entropy (disorder) of the water decreases. For any given temperature change and quantity of water, this entropy decrease can be precisely calculated. How can this be if the law demands an increased entropy for all process? The answer is that you have forgotten to look at the rest of the "universe". The decrease of disorder in the water is more than cancelled out by the increase in disorder in the molecules of air outside the refrigerator. The refrigerator pumps heat into the ouside air causing a large increase in the entropy of the room. The point then is this: Improperly limited parts of the universe do not necessarily obey the Second Law of Thermodynamics. The Law is followed only when a sufficient part of the universe is included.

If we are to believe that General Evolution contradicts the Second Law, we must then also conclude that all living organisms continually violate the Law.

Freezing Lake Michigan

It may be argued that my example was an artificial process and that evolution is supposed to be natural or operative without human intervention. Then let me choose another example. It can hardly be denied that Lake Michigan undergoes a yearly entropy change. Every winter large quantities of ice are formed. The total entropy changes involved are many times greater than those for the glass of water, yet they still involve only the cooling of water. I do not anticipate disagreement when I say that this is as "natural" a process as can be desired. Yet here again, if only the entropy change of the lake upon freezing is noted, you will conclude that you see a violation of the Second Law. Again, if attention is given to the changes in the atmosphere, differences in radiation received from the Sun, infra-red radiation from the Earth etc., the Second Law will be found to hold true.

Protein Molecule

Therefore, we must conclude that an evolutionary process which creates an isolated area of decreased entropy (increased order) does not at all defy the Second Law of Thermodynamics. If we include all involved systems, we will see that the law holds. The hypothetical case of a protein molecule formed in a thin "broth" of "organic" materials by evolutionary processes can serve as an example. The molecule is a much more ordered situation for the atoms which form it than that in which they previously existed. But the disorder of the "broth" will increase when the molecule is formed and its increase will more than compensate the decrease due to the formation of the molecule.

All Living Organisms

It should be noted that the processes of all living organisms are processes of organization. Thus, all living organisms are continually increasing the order of the molecules and atoms which they take in for nourishment. If then we are to believe that General Evolution contradicts the Second Law, we must then also conclude that all living organisms continually violate the Second Law. Both conclusions are, of course, erroneous. Nevertheless, this continual, large scale, ordering in a universe which is supposed to be running down is sufficiently curious to have arrested the attention of a few physicists. At least one theoretician has made an attempt to explain this in terms of quantum mechanical models.2

Mathematical Improbability

The argument from the Second Law is sometimes confused with the argument from mathematical improbability, but they are, in fact, distinct. The general theory of Evolution is a fantastically improbable theory in a mathematical sense and I think this is an important weakness. I know of no other theory which at all approaches the improbability of General Evolution. Unfortunately, the argument from the Second Law of Thermodynamics is not in the same sound position.


1Wilder-Smith, A. E., Man's Origin, Man's Destiny, Harold Shaw, Wheaton, Illinois, 1968.
2Frohlich, A., "Energy Storage and Long Range Coherence in Biological Systems", International Journal of Quantum Chemistry II 691 (1968).