The Second Law of Thermodynamics and Evolution

The Second Law of Thermodynamics and Evolution August 14, 2018

MrHsandsomeToad here at ATP is going to provide a few guest pieces, and he is here providing grist for the mill on something that creationists claim contradicts evolution: the Second Law of Thermodynamics.

Their argument runs like this:

  • 1. Evolutionary theory contends that current species developed from earlier life forms.
  • 2. These earlier life forms were simpler in having fewer capabilities and less complex systems.
  • 3. Therefore, evolutionary theory claims that organisms get better ordered over time.
  • 4. The second law of thermodynamics holds that entropy increases; that is, systems over time become more disordered.
  • 5. Therefore, both evolutionary theory and the second law of thermodynamics cannot both be correct.
  • 6. Physics is a more basic or well-established field than biology.
  • 7. Therefore, we ought to prefer the second law of thermodynamics and reject evolutionary theory.

Here MrHandsomeToad sets it out:

Biological evolution does not contradict the Second Law of Thermodynamics.  People who say it does, either do not understand evolution, or do not understand the Second Law of Thermodynamics, or both.  Usually, both.

First of all, the Second Law of Thermodynamics does not say “disorder must increase”; that is a popular bastardization of the Second Law of Thermodynamics.  The Second Law of Thermodynamics says “heat cannot of itself pass from one body to a hotter body”.  This does sort of imply that disorder must increase, though, so let’s accept the bastardization.  EVEN SO, biological evolution does not contradict the Second Law of Thermodynamics, for three reasons:

1.  Contrary to what evolution-deniers say, biological evolution does not always increase order within the evolving species.  Sometimes, descendant organisms are more DISordered than their progenitors.

2.  Even when evolution increases order within the evolving species, this still does not violate the Second Law of Thermodynamics, because the Second Law of Thermodynamics only requires that TOTAL disorder in the WHOLE SYSTEM must increase.  Evolution can increase order within the evolving species, without violating the Second Law of Thermodynamics, provided the increase in order is offset and counterbalanced by a greater increase in disorder elsewhere in the system.

3.  Even if evolution increases order within the evolving species, and even if the increase in order is NOT offset and counterbalanced by a greater increase in disorder elsewhere in the system, this STILL would not violate the Second Law of Thermodynamics, because the Second Law of Thermodynamics only applies to CLOSED systems.  The Earth is not a closed system: it receives a continuous influx of energy from the Sun.  So the Second Law of Thermodynamics does not, and should not, apply to life on planet Earth.

Schrieber and Gimbel have written a paper well worth reading (“Evolution and the Second Law of Thermodynamics: Effectively Communicating to Non-technicians”), which includes:

Among the chief errors of this argument are (a) its understanding of the second law of thermodynamics and the notion of entropy, (b) the scope of the application of the second law of thermodynamics, and (c) failing to understand the way in which the mechanisms underlying genetics are perfectly in line with physical law. What is needed are ways to effectively communicate these flaws to the general public.
The paper does exactly that.

Thanks very much to MrHandsomeToad. If anyone else fancies contributing to ATP, then please let me know.

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