Science Forums 2

[CraigD]

Originally Posted by Shubee

It seems that George Gamow's well-known popularization of modern physics is regarded as an acceptable view of physics. Please note the references from scholarly works: Mr Tompkins in Paperback - Google Book Review.

Gamow’s popular science books had a great and formative impact on me a youth – in particular “One, Two, Three...Infinity”, which, like the author of the linked article, I read around the age of 10, and despite understanding only a fraction of its details, practically devoured. Although I didn’t encounter the Mr. Tompkins books until nearly a decade later, and have only read the first two “in paperback” ones, I enjoyed them thoroughly, and recommend them highly.

I think Shubee misreads chapter 9 “Maxwell’s Demon” of “Mr Tompkins in Paperback”. It’s an exploration of statistical temperature fluctuations in gas (or liquids) and the old thought experiment/question/paradox of Maxwell’s demon. These ideas are all classical, not quantum mechanical. Although, as the autobiographical old professor in the story explains, events such as the spontaneous boiling of the surface of a glass of cold water (an iced alcoholic beverage, actually) are so unlikely that observing all of the glasses of cold water that will ever exist in billions of years are unlikely to witness such an event, the probability is much greater than that of a room-temperature macroscopic exhibition of quantum effects.

Moreover, the story doesn’t account an instance of such an vastly unlikely event occurring, but the professor incorrectly believing that he, Tomkins, and Maud had witnessed such an event, when actually a real (and invisible, and quite charming) Maxwell’s demon had caused it to happen.

Also, despite being amusing and educational, the professor incorrectly describes Maxwell’s demon, saying

Maxwell’s Demon is supposed to be rather a fast fellow, and capable of changing the direction of every single molecule in any way you prescribe.

As described by Maxwell and other physicist, however, and importantly, the demon can’t do physical work such as accelerating gas molecules at all, but can only open and close an arbitrarily efficient door to separate fast from slow molecules. The usual thought experiment involves this sorting being used to move a piston, but, as in Gamow’s story, it could as easily involve creating a region of boiling water in a glass of cold water.

Although the Maxwell’s demon thought experiment was originally intended as a paradox suggesting something wrong with the idea, we now know that such a thing is in principle possible, yet doesn’t, as Maxwell believed, violate the 2nd law of thermodynamics, as Szilard’s engine variant illustrates. (see this post and others for discussion and references to Szilard’s engine)

Most importantly, though, I believe Shubee misunderstands the nature of Gamow’s science popularizations. These are not scholarly works or scientific papers or textbooks, but popularizations, intended to acquaint readers in a whimsical and amusing manner with scientific ideas. As in the above example, the story about a conversation with a trick played by an actual, anthropomorphic Maxwell’s demon is not intended to describe actual reality, but to explore ideas. Unlike the black holes and Big Bang in “One, Two, Three…Infinity”, Gamow is not claiming in “Mr Tompkins” that there really are naturally occurring Maxwell demons, nor even that temperature fluctuations have ever caused the surface of an iced highball to spontaneously boil.