Evolution Violates The Second Law of Thermodynamics
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[edit] Definition
The claim that evolution violates the second law of thermodynamics is an argument against evolution based on a misconception of the Second Law of Thermodynamics. Creationists (falsely) argue that the second law of thermodynamics means all systems should tend toward disorder, and evolution implies things become more orderly over time, therefore evolution is contrary to the second law of thermodynamics.
[edit] Origins
The argument became popularized in Henry Morris' 1974 book Scientific Creationism:
- The Second Law of Thermodynamics is particularly important in this discussion, since it states that there exists a universal principle of change in nature which is downhill, not uphill, as evolution requires. (p 38)
- For the evolution of a more advanced organism, however, energy must somehow be gained, order must be increased, and information added. The Second Law says this will not happen in any processes unless external factors enter to make it happen. (p 40)
[edit] Discussion
The simplest way to see that the creationist argument is wrong is to observe that one way of stating the Second Law of Thermodynamics is to say that you can't build a fridge without a power source. Anything that violates the Second Law of Thermodynamics would therefore imply a way of building such a fridge, which evolution does not.
The creationist mistake appears to have originated with a failure to distinguish between two other forms of the same law: this confusion is often perpetuated in serious discussion of the second law of thermodynamics, so we shall try to make the point clear.
On the one hand, we may state the Second Law as:
- ∆Sisolated ≥ 0
That is:
- Over any process in an isolated system the entropy cannot decrease.
On the other hand, we may equivalently state it as:
- ∆Ssys + ∑∆Ssurr ≥ 0
That is:
- Over any process, the total entropy of a system and its surroundings cannot decrease.
We shall demonstrate that these two statements are equivalent. The first statement implies the second, for we may take the system and its surroundings to be one big isolated system. And the second statement implies the first, for if the system is isolated, the process cannot increase the entropy of the surroundings, so we have ∑∆Ssurr = 0 and the result follows.
For further information, here is an online textbook of thermodynamics. [1]
Now the question is, which version should we apply to the Earth and its biosphere? And we note that the Earth is not at all an isolated system, as it receives low-entropy energy (sunlight) and gives off high-entropy energy (heat). Therefore, it is the second statement which applies.
So evolution on Earth can decrease the net entropy of the Earth, so long as this does not cause a decrease in the net entropy of the Earth and its surroundings (the rest of the Universe). Which it does not.
[edit] References and resources
An online textbook Çengel Y. A. & Boles M. A., Thermodynamics [2] (see especially pages 7.13-14.)
Perpetuating the Myth
- Morris, Henry M., 1974. Scientific Creationism, Green Forest, AR: Master Books, pp. 38-40.
Debunking the Myth
- [3] Harvey, Allan A. "The Second Law of Thermodynamics In the Context of the Christian Faith."
[edit] Related Articles
[edit] Appendix: unconscious humor
The following quotation is not typical of the creationist argument, but is included because of its unintentional comic aspects.
"One of the most basic laws in the universe is the Second Law of Thermodynamics. This states that as time goes by, entropy in an environment will increase. Evolution argues differently against a law that is accepted EVERYWHERE BY EVERYONE. Evolution says that we started out simple, and over time became more complex. That just isn't possible: UNLESS there is a giant outside source of energy supplying the Earth with huge amounts of energy. If there were such a source, scientists would certainly know about it." [emphasis added]
- awesomestnerd, SmashBoards
