Entropy

The concept of entropy is one that runs throughout "The Information" and ties information theory to the fields of mathematics, quantum physics, and molecular biology. It is a complex concept and one that Gleick tries to explain in detail.

The term was first used in reference to thermodynamics in the 19th century, Gleick explains. It was noticed that if a hot object was placed next to a cooler object, the heat would move from the hot object toward the cold. As energy moved, it provided potential to do work similar to when steam was released. Eventually, in any closed system, the temperature would stabilize and no energy was available to do any work. Entropy was a term used to refer to this unavailability of energy. A stable system had maximum entropy.

This tendency for energy to move in a certain direction was then defined in terms of probability...