Introduction to entropy

Entropy describes any of several phenomena, depending on the field it is being used in. (Quick basic recitation of the several uses might follow here).

Originally, entropy was named to describe the "waste heat" from engines and other mechanical devices. Later, the term came to acquire several descriptions as more came to be understood about the behavior of molecules on the microscopic level. In the late 19th century the word disorder was used by Boltzmann to describe the increased molecular movement on the microscopic level. That was before quantum behavior came to be better understood by Werner Heisenberg and those who followed. For most of the 20th century textbooks tended to describe entropy as "disorder", following Boltzmann. More recently there has been a trend in chemistry and physics textbooks to describe entropy in terms of "dispersal of energy".