Feb 262008
I recently read Arieh Ben-Naim’s book Entropy Demystified, a book I feel would have benefitted greatly from being more somewhat more focused on the task of explaining entropy than it actually was. While Ben-Naim, as promised, does a good job of reducing the second law of thermodynamics to “plain common sense”, he makes confusing decisions to include arguments better meant for experts and diatribes that serve nobody. As a result I feel the book, though largely useful, may ill-serve the lay audience for which it is apparently intended, especially as regards the areas where non-scientists are most likely to encounter the concept of entropy.

In my view, the purpose of a popular book on a scientific subject is twofold. First, it should provide readers with enough good science to understand the subject as it appears (if it appears) in their lives. Second, it should provide the lay reader with a framework that allows him to interpret the words of experts. That is, the reader should come away with an understanding of what scientists mean by (in this case) entropy. Thus, popular books on any subject are not a reasonable platform to argue for paradigm shifts. First of all, you’re not talking to your target audience (i.e. experts) when you do this. Second of all, the lay readers that agree with you will now be thinking of the subject in a very different way than most of the scientists they will encounter. So not only do you fail at what you’re intending to do in terms of serving your new paradigm, you also fail at one basic task of the popular science book. The unfortunate thing with Ben-Naim’s book is that it fails at the second task and ends up with mixed results on the first, for no real reason. He could have done just as good a job explaining entropy without introducing the new paradigm at all.

Entropy, despite its importance, is not a topic that lay people encounter very often. The transfer of heat from warmer to cooler bodies is a common example, as is the diffusion of dye in a liquid, or the mixing of two liquids or gases. Ben-Naim does an excellent job of explaining the role of entropy in these processes, building up from relatively simple dice games to complex discussions about temperature and gaseous mixtures. However, he does not do any job at all of explaining the role of entropy in reactions. Consequently, he fails to explain how apparent counteractions to entropy occur. A layman reading this book will understand why a gas expands, but not why it was possible to compress it in the first place. Also, Ben-Naim’s approach and focus on mixtures and the like will also leave the reader utterly unprepared to encounter discussions of entropy in connection to the hydrophobic effect. Could the framework here introduced be extended to explain micelle formation and protein folding? I don’t doubt that this is so, but Ben-Naim doesn’t do it, to the detriment of the book and its readers.

What’s Ben-Naim doing with all this space that he’s not using on talking about the role of entropy in chemical reactions? Well, he’s arguing for a view of entropy based on information, specifically defining entropy in terms of “missing information”. Although this position has some merits, this book is an entirely inappropriate place to make the case for it. Why? The most pervasive popular misuse of the second law of thermodynamics is in creationist canards about the thermodynamic impossibility of evolution. These misinterpretations often rest on ideas related to information (as colloquially used) or distortions of information theory. Although Ben-Naim repeatedly states (correctly) that information has a precise scientific meaning, he never graces his readers with it. I fear this leaves them more vulnerable to creationist distortions than before they started reading. That Ben-Naim says little to emphasize the meaning of “closed system” or the other parts of thermodynamics exacerbates the problem. The discussion of information was not strictly necessary to his overall point—his excellent introduction of probability would have sufficed—and it is easily misread and misused. In my opinion, he should have held his tongue here and allowed his book targeted at the academic audience (A Farewell to Entropy: Statistical Thermodynamics Based on Information) to make the case.

Ben-Naim also devotes pages and pages to complaints about other authors’ (Atkins particularly comes in for criticism) presentations of entropy. These sections contain a few good ideas, but on the whole read like petulant complaints about more popular writers. That these pages serve any real purpose at all is debatable; that they weaken Ben-Naim’s case is certain. No matter how much he disagrees with these authors it would be better for him to disregard them and focus on constructing his own case than deconstructing their books. I agree with him that science writers are too eager to portray entropy as mysterious, but clearing up the mystery is sufficient. His detailed rebuttals of their language are unnecessary.

It’s a pity, because Ben-Naim really does pack in some useful and important concepts. Strip away the unnecessary information theory, and his book does an excellent job of reducing the law of entropy to common sense. Entropy Demystified explains what entropy actually means for certain physical systems, and excels at building this picture up from very simple games that anyone can intuitively understand and model. That said, Ben-Naim does not tie entropy into real processes nearly as well as he could, and his insistence on representing entropy in a way that has not yet gained mainstream acceptance may mitigate his readers’ ability to apprehend what scientists are saying about the subject. Moreover, the fact that this alternative presentation is “entropy as missing information” is more likely to perpetuate misunderstandings about entropy (especially with regard to evolution) among the lay audience than to clear those misunderstandings up. As such, I cannot recommend this book, despite its virtues.

  2 Responses to “Arieh Ben-Naim’s Mystifying Decisions”

  1. The ST eqn derivation was an exciting part in "Farewell". But, again, Ben Naim as you rightly pointed out, leaves a lot of room for unnecessary interpretations. And that was really depressing for such a fine read.

    Thanks for sharing your review.

  2. I accidentally stumbled over your review while searching for information on Ben-Naim and his book on Google. Very well-written review. Now I can read the book with a pinch of salt.

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