Maxwell’s Demon

Among the general public, perhaps the least understood of the fundamental laws of physics is the second law of thermodynamics—the law of entropy. This law impacts upon everyday life in numerous ways. As Hans Christian von Baeyer demonstrates, hot coffee cools and cold orange juice warms because of this law, and time moves in but one direction.

Written for the lay person, MAXWELL’S DEMON: WHY WARMTH DISPERSES AND TIME PASSES is both an overview of the history of almost two centuries of discoveries in thermodynamics—focusing on the first (the conservation of energy) and second laws of thermodynamics—and a summation of the state of knowledge in the field. During these two centuries, thermodynamics has moved from the center of physical research to the periphery, where it remained through most of the twentieth century, and then, during the last few years, back to the center. During the nineteenth century, the discipline attracted a number of very colorful scientists. Von Baeyer’s character sketches are among the highlights of the book. He makes these scientists come alive.

The Demon of the title was the creation of James Clerk Maxwell in 1867. Could such a Demon sort molecules in such a way as to violate the second law? Maxwell wasn’t sure. Subsequently, physicists have demonstrated that the Demon could not violate the law, just to have other physicists change the attributes of the Demon and resurrect the problem. In short, the Demon can be viewed not only as a particular component of a particular theory, but as a symbol of the ingenuity of scientists in their efforts to understand the nature of the universe.