Warmth Disperses and Time Passes deals with, among other things, "Maxwell's Demon," a metaphorical device invented by James Clerk Maxwell a century and a half ago in an attempt to expose flaws in the second law of thermodynamics. This imaginary demon would sit between two flasks of air and allow only warm air molecules to enter the warmer flask. This would cause heat to flow uphill--a death knell for the second law if it were possible. Only it wasn't; it was the death knell for the demon instead. Successive "improved" demons were invented by later physicists, but all have subsequently been killed. The realization that a live demon is impossible has served to further strengthen the second law.
Hans von Baeyer is almost as much historian as scientist. As he walks us through the evolution of scientific understanding of thermodynamics, he stops to dwell on the intellectual and societal framework that allowed the physicists of the time to make their respective scientific leaps. This blend of science and history, combined with von Baeyer's journalistic approach, creates a book that is both exceedingly accessible and surprisingly illuminating. --Eric Warner [via]