Everything You Ought to Know About Thermodynamic Laws : MAXWELL’S DEMON, Why Warmth Disperses and Time Passes, by Hans Christian von Baeyer, Random House, $25, 207 pages

“Things fall apart,” wrote William Butler Yeats in 1920, neatly describing not only the moral and political chaos of the human universe, but also the second law of thermodynamics. The second law--that heat flows naturally from hot objects into cooler objects and never the other way around--might seem pedestrian to any working stiff who has stood waiting for an elevator, paper bag in hand, his drugstore coffee warming up his cold bottle of orange juice. But the implications of the second law, especially under its colloquial name of the law of entropy, have excited 20th century writers from Yeats to Thomas Pynchon and Chinua Achebe.

And yet the front ranks of physicists, beginning with Albert Einstein in 1905, have shrugged their shoulders along with the working stiffs, paying more attention to the relativistic mechanics of elevators than to the warmth of drugstore coffee. With “Maxwell’s Demon,” physics professor Hans Christian von Baeyer attempts to correct that astigmatism and show how the study of heat is central to the physics of the new millennium.

The great-grandson of one of the principal players of 19th century thermodynamics, Von Baeyer naturally tells the story of the discoveries of the laws of thermodynamics through the biographies of its students: German physician Robert Julius Mayer, French military engineer Sadi Carnot, British spy Count Rumford, and Rudolf Clausius, James Joule and Ludwig Boltzmann, whose names will be more familiar to students of physics.

At the center of the book is Scotsman James Clerk Maxwell and his famous demon, an imaginary assistant to whom Maxwell set the task of disproving the second law--an invisible sprite who could easily fit within a paper bag and reverse the flow of heat, taking the warmth of the orange juice and giving it to the coffee, ensuring a perfect breakfast.

Of course the demon is always doomed to failure. The second law is, after all, a law. The “downhill” flow of heat from a warm cup to a cold glass is inexorably linked to the forward movement of time. Neither heat nor time stop for man nor demon. And yet as Von Baeyer shows with great excitement, there are still, a hundred-odd years later, scientists who refuse to write the demon off as dead and are busy rehabilitating him for other uses.

Von Baeyer may not be the most elegant of storytellers, occasionally stumbling on his own parables with the self-conscious cleverness of a professor in front of a class of freshmen. Sometimes, as in the tragic story of the misunderstood and suicidal Mayer, he pulls the blinds just when the voyeur in us wants to see the alchemical conversion of madness into recognition.

Yet it is the heat of scientific inquiry that makes “Maxwell’s Demon” not just a lucid but a compelling read, a primer not so much for reading physics as for reading poetry and Pynchon. And for understanding exactly what fundamental things apply, as time goes by.