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Creationists argue that evolution violates the second law of thermodynamics. How do scientists respond?
David H. Bailey
1 Jan 2013 (c) 2013
Creationism's claim for the Second Law of Thermodynamics
For many years numerous creationists have cited the second law of thermodynamics as fundamental evidence that the scientific account of the cosmos evolving from the big bang in general, and biological evolution in particular, cannot occur. They argue that since the operation of evolution is towards higher and higher levels of organization and complexity, evolution violates the second law and thus fundamentally cannot occur. For example, a prominent creationist cite declares [SecondLaw2011]:
However, this basic law of science (2nd Law of Thermodynamics) reveals the exact opposite. In the long run, complex, ordered arrangements actually tend to become simpler and more disorderly with time. There is an irreversible downward trend ultimately at work throughout the universe. Evolution, with its ever increasing order and complexity, appears impossible in the natural world.
For many readers, not schooled in the intricacies of thermodynamics and physics, this is an impressive-sounding argument. Is this indeed an effective refutation of evolution?
Scientific background on the Second Law
The second law of thermodynamics is an expression of the universal principle of entropy, namely that the entropy of an isolated system which is not in equilibrium will tend to increase over time, approaching a maximum value [Wikipedia2009]. At a fundamental level, this is really a statement about probability, because it is equivalent to saying that any system will, with very high probability, tend to a "disordered" state. For example, if billiard balls are placed on a billiard table in the triangle frame, and then scattered by a cue, it is overwhelmingly more likely that when they all stop moving they will be in a rather "random" configuration, rather than, say, in a highly ordered configuration such as all in one corner. The reason for this is pretty simple -- the number of "random" configurations of billiard balls on a billiard table are vastly more numerous than the number of highly ordered configurations.
The creationist argument's fallacy
A key condition of the second law is that the system being described is a "closed system," in particular one that has no influx or outflow of energy [Patterson1983]. Unfortunately for creationists, this is where the application of the second law of thermodynamics to evolution breaks down: the earth's biosphere is most definitely not a "closed system." To the contrary, every day for several billion years the earth has received solar energy in the amount of 10,000 times the total daily energy consumption of the entire present-day human civilization. Indeed, biology can be seen as a process that extracts energy from the environment to create order and complexity. This was perhaps best expressed by physical chemist Ira Levine back in 1978 [Levine1978, pg. 123-124]:
Increasing entropy means increasing disorder. Living organisms maintain a high degree of internal order. Hence once might ask whether life processes violate the second law. ... The statement [that entropy cannot decrease] applies only to systems that are both closed and thermally isolated from their surroundings. Living organisms are open systems since they both take in and expel matter; further, they exchange heat with their surroundings. ... The organism takes in foodstuffs that contain highly ordered, low-entropy polymeric molecules such as proteins and starch and excretes waste products that contain smaller, less ordered molecules. Thus the entropy of the food intake is less than the entropy of the excretion products returned to the surroundings. ... The organism discards matter with a greater entropy content than the matter it takes in, thereby losing entropy to the environment to compensate for the entropy produced in internal irreversible processes.
In short, the "thermodynamics argument" against evolution is completely groundless. Some creationists have discontinued using this argument, but it is promoted at length in the 2000 printing of Morris' Scientific Creationism [Morris2000, pg. 38-46], and it is also featured prominently in the museum of the Institute for Creation Research in San Diego, California.
One can certainly fault creationists for continuing to use an argument that they know (or should know) is fallacious. But, as John Patterson has observed, the scientific community is also at fault: "It is a sad testimonial to the community of professors, engineers, and scientists that so many have ignored their professional responsibilities in failing to expose the creationist thermodynamics apologetic." [Patterson1983].
See also Novelty.