Friday, March 25, 2011

The Second Law and Creationism

This post is part of a series,Nonsense and the Second Law of Thermodynamics. The previous post is entitled Entropy and Information Theory.

Creationists and other people confused about the second law of thermodynamics  often bring up some variant of the idea that life is somehow a counter-example the second law of thermodynamics.  If entropy were disorder (which it is not), is it not obvious that life is highly ordered?

Therefore they seem to conclude that life is an example of decreasing entropy. The flaw in their thinking is not so much the confusion between disorder and entropy; the argument could be made with an accurate description of entropy. It would still be incorrect.

An Open System

The second law does not state that a system's entropy cannot decrease.   It says that a closed system's entropy cannot decrease.  Life, as we know it, is not a closed system.  Life exists in an environment with energy streaming in and out from the surroundings.

The most obvious problem is the sun.  The sun is streaming energy to the earth.  What we earthlings do with that energy is negligible compared to what happens on the sun.

Even if we could somehow exist without the sun, our energy has to come from somewhere.  When we eat we get energy, but we must emit waste products.  The energy that we living things consume is not all used for useful work; much of it is given off as heat.

The second law regulates the upper limit on useful work that can be done with the amount of energy used.

Living things create entropy every time they take action.  Any local decrease in entropy must be paid for by an increase in the entropy of the environment.  In fact, it must be paid with interest.

Creationism and Entropy

A primary example of a Creationist using such a flawed argument is Henry M. Morris, Ph.D. in his article: The Scientific Case Against Evolution
The main scientific reason why there is no evidence for evolution in either the present or the past (except in the creative imagination of evolutionary scientists) is because one of the most fundamental laws of nature precludes it. The law of increasing entropy -- also known as the second law of thermodynamics -- stipulates that all systems in the real world tend to go "downhill," as it were, toward disorganization and decreased complexity.
Note that the author in this case tries to argue with the obvious flaws in his argument:
This naive response to the entropy law is typical of evolutionary dissimulation. While it is true that local order can increase in an open system if certain conditions are met, the fact is that evolution does not meet those conditions. Simply saying that the earth is open to the energy from the sun says nothing about how that raw solar heat is converted into increased complexity in any system, open or closed.

The fact is that the best known and most fundamental equation of thermodynamics says that the influx of heat into an open system will increase the entropy of that system, not decrease it. All known cases of decreased entropy (or increased organization) in open systems involve a guiding program of some sort and one or more energy conversion mechanisms.

The argument here is a beautiful piece sophistry.  To prove that evolution does not violate the second law of thermodynamics, those of us who believe in Evolution must now prove every link in the chain.

We must show how plants convert sunlight into stored energy in the form of reduced forms of carbon.  We must show that this process is not 100% efficient, but that some of that some of the energy must be discarded as heat.  We must trace the use of this reduced carbon through the food chain and show that each time it is oxidized to do useful work that some energy must be dissipated as heat.

All of the processes by which life converts energy to do something useful follow the second law of thermodynamics.  The second law is not some vague pronouncement about order and disorder.  It is a precise thermodynamic quantity that can be measured.

Morris's argument is beautiful because it moves the missing link paradox to the realm of thermodynamics.  The missing-link paradox is that Creationists claim that intermediate forms between other primates and humans have never been found.

When somebody find a species  N that is intermediate between species B and species W, the Creationist can respond that no one has found a species intermediate between species B and species N.  The Creationist can play this game forever, no matter how many intermediate species are found, even if we exhaust the letters of the alphabet.

Anyone who takes up Morris's argument must now do the same thing for each process in which a living organism converts energy to useful work.  In other words, it is necessary to understand everything about every possible biological process.

Until we understand everything, Morris can gleefully state that Evolution is "unproved."  He does not need to compare the explanatory power of Evolution to his alternative hypothesis.

Once life exists, the mechanisms of evolution and life involve genetics, genetic mutation. and natural selection.  These processes are, of course, constrained by thermodynamics.  The process of reproduction requires energy, not all of that energy can be used for useful work.  Living things must produce waste products and heat to reproduce.

The Origin of Life

The question of the origin of life  is conceptually different from the question of evolution, but it is still an important subject for thought, and it is a related question.

The origination of the first living cell is a conceptually difficult topic.  We do not know precisely how life came to be despite decades of research from the days of A. I. Oparin.   The event could have been a singular event, i.e., all life evolved from a single occurrence of a cell becoming alive.  Alternatively, multiple events could have occurred under some optimal condition.

It is not unreasonable to suppose that whatever happened was statistically unlikely.

Such an even is statistically unlikely enough that it has never been observed directly.  It is possible that under certain conditions it may be more probable. It is possible that this event was singular that it only happened once, but we do not know that.

That statistical unlikelihood does not make it a violation of the second law of thermodynamics!

The nascent cell, like all other thermodynamic processes, must have required energy.  Some of that energy was used to do useful work, but not all of it.  The entropy of the system, i.e., the nascent cell, and the surroundings, i.e., everything else increased according to the second law.

There is no thermodynamic problem for the origin of life.  Do not confuse statistical arguments for the unlikelihood of life's origin with statistical thermodynamic arguments about entropy.  The occurrence of a statistically unlikely event is not inconsistent with the second law of thermodynamics.

That is not to say that we know everything there is to know about how life came to be.  Not knowing how something happened does not make it a violation of the second law. The next post is entitled Entropy as a Religious, Spiritual or Self-Help Metaphor.

Sources
• Atkins, P. W. Physical Chemistry, W. H. Freeman and Company, New York, 3rd edition, 1986
• McQuarrie, Donal d A., Statistical Thermodynamics,  University Science Books, Mill Valley, CA, 1973
• Bromberg, J. Philip, Physical Chemistry, Allan and Bacon, Inc., Boston, 2nd Edition, 1984
• Anderson, H.C., Stanford University, Lectures on Statistical Thermodynamics, ca. 1990.
• Henry M. Morris, The Scientific Case Against Evolution
• A. I. OparinThe Origin of Life
• Wikipedia: Arcaeopteryx Lithographica Paris