Over at Uncommon Descent, there’s a bit of a kerfuffle going on about the second law of thermodynamics. Salvador Cordova got the ball rolling back in July with this barn-burner of a post excoriating his fellow ID proponent Granville Sewell for making bad thermodynamical arguments:
ID proponents and creationists should not use the 2nd Law of Thermodynamics to support ID. Appropriate for Independence Day in the USA is my declaration of independence and disavowal of 2nd Law arguments in support of ID and creation theory. Any student of statistical mechanics and thermodynamics will likely find Granville Sewell’s argument and similar arguments not consistent with textbook understanding of these subjects, and wrong on many levels. With regrets for my dissent to my colleagues (like my colleague Granville Sewell) and friends in the ID and creationist communities, I offer this essay. I do so because to avoid saying anything would be a disservice to the ID and creationist community of which I am a part.
I’ve said it before, and I’ll say it again, I don’t think Granville Sewell 2nd law arguments are correct.
Wow! Pardon my surprise, but that’s actually pretty good.
There have been several more rounds, culminating with this post from Sewell. It’s remarkable stuff. Here’s the money quote:
If you insist on limiting the second law to applications involving thermal entropy, and that the only entropy is thermal entropy, than Sal is right that the second law has little to say about the emergence of life on Earth. But it is not just the “creationists” who apply it much more generally, many violent opponents of ID (including Asimov, Dawkins, Styer and Bunn) agree that this emergence does represent a decrease in “entropy” in the more general sense, they just argue that this decrease is compensated by increases outside our open system, an argument that is so widely used that I created the video below, Evolution is a Natural Process Running Backward to address it a few months ago.
In case you missed it, that’s Sewell conceding defeat. That first sentence is a doozy. When you are talking about the second law of thermodynamics, there is only one kind of entropy. The issue is not that some unimaginative critics of ID simply refuse to apply the second law in its full generality. It is that the second law is a very specific statement regarding the magnitude of the change in entropy that can occur in certain physical processes, and if you understand that statement then you also understand that neither evolution nor the origin of life runs afoul of it. That’s the end of the discussion.
The rest of Sewell’s paragraph is the sheerest lunacy. For example, his reference to Asimov is to this quote, from earlier in his post:
We have to work hard to straighten a room, but left to itself, it becomes a mess again very quickly and very easily … How difficult to maintain houses, and machinery, and our own bodies in perfect working order; how easy to let them deteriorate. In fact, all we have to do is nothing, and everything deteriorates, collapses, breaks down, wears out—all by itself—and that is what the second law is all about.
This is not Asimov “applying” the second law to the problem of straightening out a room. This is him making an analogy to help lay readers understand the gist of the second law.
Moreover, when scientists refer to the origin of life as representing a decrease in entropy, they are not applying some generalized version of the second law to problems beyond the original domain of its formulation. They are simply saying that even if we make the assumptions about the entropy change involved in the origin and evolution of life that are the most favorable to the anti-evolution side, you are still nowhere close to obtaining a contradiction with the second law. That the second law allows for local decreases of entropy so long as they are offset by increases elsewhere is not some desperation argument summoned forth by anti-ID propagandists. That’s just a straightforward consequence of what the second law says.
Elsewhere in the post, Sewell serves up his usual silliness about other forms of entropy:
Thermodynamics texts, as opposed to general physics texts, tend to shy away from them for that reason. Goodness knows, if we watch a video of a tornado tearing through a town, it is so difficult to quantify what we are seeing that we can never be sure if the video is running forward or backward, or if entropy is increasing or decreasing. But there are other types of “entropy” which are as quantifiable as thermal entropy, for example, the “X-entropy” which measures disorder in the distribution of any diffusing component X is defined by essentially the same equations as are used to define thermal entropy, which measures disorder in the distribution of heat as it diffuses, and X-entropy is certainly equally quantifiable. And X-entropy has little or nothing to do with thermal entropy (doesn’t even have the same units), one can increase while the other decreases in a given system. So why do people like Styer and Bunn and Sal, insist on treating all types of entropy as thermal entropy, and attempt to express the entropy associated with evolution, or the entropy of a 747, in units of Joules/degree Kelvin?
Physicists like Styer and Bunn are applying the only notion of entropy that is relevant to applications of the second law. That you can define other physical quantities and attach the label “entropy” to them is neither here nor there. Not, at least, unless you can also give a mighty good argument for why the second law still applies to your new quantity.
As I have argued before, the second law of thermodynamics does not actually play any role in creationist or ID argument. When you hear them refer to the second law, you can be sure that they are just expressing incredulity that evolution can lead to increases in complexity. Invoking the second law is strictly a way of putting a scientific gloss on an entirely vacuous argument.