Preposterous Universe

Monday, May 30, 2005
Entropy and intelligence

In the comments to the previous post, PZ complains (rightfully) about creationists who claim that only intelligence can lead to the decrease in entropy of an open system that is required to explain the complexity of life. A crazy claim, of course, since the Second Law only applies to closed systems, so open systems are perfectly free to have their entropy go up or down (as they do all the time).

Fortunately, last week we had a nice physics colloquium by Ron Walsworth, who provided a simple example on which we can test the hypothesis that only intelligence can decrease entropy (or disorder, or whatever). Consider the following system: a rectangular container filled part way with tiny spheres, some of them made of glass and some of brass. All the spheres have equal size, but the brass ones are heavier than the glass ones. Okay, now please tell me which of these configurations has the lowest entropy (or highest order, or greatest complexity, or whatever it is that you think only intelligence can bring into existence):
  • Brass spheres on top, glass on the bottom
  • Glass spheres on top, brass on the bottom
  • Spheres perfectly mixed
  • Some interesting striped pattern
Have you made your choice? Good. Now we do the following experiment: we just jiggle the container. There are a few free parameters here -- the amplitude and frequency of the jiggling, along with the density of gas in the container. It seems to me that your hypothesis has led to a prediction: namely, that whatever configuration you think is low-entropy (or highly ordered, or most complex, or whatever) will not be achieved by simple jiggling, it would require an intelligent agent to bring it about. So, make sure you've made a clear choice about which it is, and we'll do the experiment.

And the answer is: you're wrong. No matter what configuration you picked. The plain truth is, each of the various configurations is achieved by simply jiggling the system, for some value of the free parameters. Nothing intelligent went into it. Since you have now been proven incorrect, I am confident that you won't be bringing up this canard any more.

Actually, I'm quite confident that this little demonstration will have no effect on you at all. I'm sure you will somehow fix up your definitions so that this example doesn't apply, just as you would do for any other example. People who want to disbelieve in natural selection aren't swayed by logical arguments and the scientific method; they are wedded to their convictions with a passion that transcends mere rationality. But we can try.

Ideas on culture, science, politics.
Sean Carroll

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