Wednesday, March 08, 2006

Evolution and the Second Law

Creationists have long tried to claim that the Second Law of Thermodynamics contradicts the Theory of Evolution. That’s to be expected, since Creationists generally don’t bother to learn anything about thermodynamics before making the claim. The Intelligent Design crowd has generally tried to look more scientifically savvy, but one of their lead proponents, William Dembski, has recently linked to a thermodynamics-based anti-evolution argument by Granville Sewell.

The anti-evolution argument goes something like this: The Second Law of Thermodynamics says that no process exists which can cause the entropy of a system to decrease. Since entropy is chaos, this law means that the chaos of a system can’t decrease. If the chaos can’t decrease, the order can’t increase. If no natural process can increase the order of a system, the process of evolution can’t account for the increase in the order and complexity of living organisms over time. Evolution is destroyed! God created life! Hallelujah!

Rubbish, because that’s not what the Second Law of Thermodynamics says. Technically, it says that no process can exist that only moves heat from a cool place to a warm place. The expanded definition is that the entropy of a closed system can never decrease.

There’s that word – “entropy” – again, but what does it mean? Entropy is energy that the system can no longer use in its process. The simplest example of entropy is waste heat. If you spin a wheel, it slows down because friction at the axle turns the kinetic energy of the wheel into heat. The wheel eventually slows down and stops as all of its kinetic energy becomes entropy.

Note that entropy is waste energy – not “chaos”. Once you understand this simple concept, you can see why the thermodynamics argument against evolution is baseless. A living being is not a closed system, so it can easily get rid of entropy just by radiating waste heat. At the same time, it takes in new energy – in the form of food – to run its processes. That’s why scientists say it matters that living beings are open systems, as is the entire ecosystem. There is absolutely nothing in thermodynamics that prevents evolution from happening; if it did, real scientists would have killed the Theory of Evolution decades ago.

Granville Sewell – and, by extension, William Dembski – is just another charlatan trying to trick an uninformed public with lies about thermodynamics.

Credits go out to Jason Rosenhouse for drawing my attention to the joint foolishness of Dembski and Sewell and to Mike Wong for succinctly explaining why the Second Law argument against the Theory of Evolution is either ignorance or deliberate deception.


Anonymous said...

Your explanation of the 2nd Law and its implications, naive and over-simplified though it may be, is substantially correct. But the application of physical laws to matters which are inherently spiritual, and thus trancendent of the physically observable universe, are, in reality, irrelavent to cosmological theories and thus do not offer any real conclusions about the origins of life.

The Rabbi

Lord Runolfr said...

I am not claiming to have comprehensive knowledge of the origins of life. I am simply refuting a false argument commmonly used against the Theory of Evolution.

Science is not concerned with "trancendent" matters that are not observable, since the purpose of science is to decribe the observable universe. Anything that we cannot observe is inherently outside the scope of science.

It should go without saying, of course, that anything that is outside the scope of science has no business in a science class, but I'll say it anyway, because certain activists keep trying to push non-scientific explanations of the origins of life into science classes.

David Harmon said...

Just to cover another base, it's worth mentioning that the Earth as a whole is not a closed system, having both a massive energy source (the Sun) and a big heat sink (the open sky).

TC said...

A contributing factor to the misuse of the 2nd law to evolution is that too many people, science teachers included, misuse entropy. My two favorite examples are the stereotypical teenager's messy room and a shuffled deck of cards. Neither possess a higher state of entropy compared to their neat and ordered versions, but physical science teachers everywhere cite them as examples of entropy increase. Entropy is all about energy distribution. As the energy distribution increases (i.e. as the energy spreads out), the entropy increases. Now if we can just get the perpetual motion machine wackos to stop misuing the term free energy we'll really have something.

Intelligent Designer said...

It's a mistake to think of entropy only in terms of themodynamics. Entropy also applies to information. While the sun adds energy to the earth it doesn't add information. DNA contains information.

Can you provide one example of how adding energy to a system produces information?

Lord Runolfr said...

No, but I can tell you that "information" gets added to DNA every time gene duplication occurs, and that's a fairly common mutation. With a duplicated gene, information is added to the genome, and one of the copies can freely change without breaking anything in the species.

Besides, the whole "you can't personally answer this question, so there must be no answer" ploy is typical.

Why don't you tell me what ID theory predicts that can be tested, keeping mind that "ID can predict anything" is exactly the same thing as saying "ID predicts nothing".

Lord Runolfr said...

I suppose I could actually point out that a gene-duplication mutation actually requires energy to happen, so energy input into the organism does have at least one known mechanism for adding information.

In fact, the energy coming from the sun actually powers pretty much all of the chemical reactions required for life as we know it, so it's not hard to draw the conclusion that yes, yes... energy does in fact add information to the ecosystem.

Intelligent Designer said...

Your example only shows how energy can be used to copy information.

Entropy, when applied to information, means that the more information is copied, the more copy errors there will be. More copy errors mean less information.

Entropy Versus Evolution includes a discussion about copy errors during cell division.

Lord Runolfr said...

There is no clear link between entropy in the thermodynamic sense and the "Shannon entropy" discussed in information theory. Even if there were, removing entropy from a system requires either work (energy) or an external "heat sink" that is "cooler" than the system (as waste energy will spontaneously migrate out of the system in order to increase overall entropy in such a situation).

The point of gene duplication is that when you have two working copies of a coding gene, the organism can produce the resulting protein from either one. The "backup copy" can then mutate without depriving the organism of a that protein. An imperfect copy at this point can actually produce a different protein which may or may not be useful, depending on the situation. Useful or not, the genome is now coding for an additional protein that it wasn't encoding before. The "information" content of the genome has increased.

Intelligent Designer said...

So your point is that a random mutation to inforpation results in more znformation?

Lord Runolfr said...

A duplication of "information" that then mutates to "inforpation" would, in fact, result in an increase in the information content of the genome, if you aren't foolish enough to assume that "inforpation" would be a useless change.

Since you seem to like using words as an analogy for gene "information" content, let's use the gene "them" as an example.

"Them" has become a required gene for our hypothetical species. It could easily mutate into a valid gene like "the", "then", or "theme", but without the gene "them", the organism wouldn't survive to reproduce.

A gene duplication event occurs in our species, so now a a descendant has two copies of "them" in its genome. Either one can fulfill the requirement for the organisms to have a "them" gene, so the second copy can now mutate into "the", "then", or "theme" without breaking the requirement for a "them" gene. We'll assume that one of our organisms mutates to develop a "then" gene.

The old genome:

The intermediate genome:

The new genome:

We have now increased the information content of the genome. If the "then" gene is helpful, or at least harmless, to the organism in its environment, it will remain in the gene pool of the organism's descendants. Further duplications and mutations can add considerable variety to the genome.


...and so on. Basically, the information content of the genome can easily increase as a result of mutation.