"entropy is disorder" = outmoded theory?? The wikipedia article I quote below is confusing me. I followed the links to Frank Lambert's website, where he claims that Peter Atkins, in the 8th edition of his Physical Chemistry, has come around to Lambert's idea that entropy is not related to disorder. Could this be true? I would be less surprised to learn that Atkins had become a born-again Christian. However, according to my old-fashioned understanding of entropy, even very improbable things happen occasionally, given a sufficiently huge number of trials. Seriously, I was about to start reading the 7th edition of Atkins Physical Chemistry, but now I'm wondering if I should look for a more reliable author. http://en.wikipedia.org/wiki/Introduction_to_entropy Traditionally, 20th century textbooks have introduced entropy as order and disorder so that it provides "a measurement of the disorder or randomness of a system". It has been argued that ambiguities in the terms used (such as "disorder" and "chaos") contribute to widespread confusion and can hinder comprehension of entropy for most students. A more recent formulation associated with Frank L. Lambert describing entropy as energy dispersal describes entropy as measuring "the spontaneous dispersal of energy — at a specific temperature." http://entropysite.oxy.edu/ March 2006 Atkins' "Physical Chemistry" has been the best selling text worldwide in this subject for many years.* The new 8th edition was published in the US March 16. However, in previous editions Atkins described systems and entropy change in terms of order and disorder or chaos.* Even though he long has used the phrase, "the dispersal of energy", it was confined to an order-disorder view of thermodynamics — for example, to spontaneous changes being "always accompanied by a dispersal of energy into a more disordered state".** (Or "to chaos" in his book "The Second Law".) In contrast to the Second Law chapter of the 7th edition, which had some 27 instances of using "order to disorder" as a rationale for change, "disorder" and "disorderly" are mentioned only 3 times in the new 8th edition.* Atkins, with co-author dePaula, now state that their view of entropy "summarized by the Boltzmann formula is consistent with our previous statement [earlier in the chapter, re the dispersal of energy in classical thermodynamics] that the entropy is related to the dispersal of energy.