The simplicity of entropy

With entropy law, it is very clear why external resources are essential for all biological and economic activities. With the concept of energy, it will be more difficult to understand why external resources are essential.

Entropy law is widely considered the most universal law in nature. This understanding is what drives the use of entropy as a basic variable in the research work of some pioneers. Planck used entropy in deriving the formula of quantum. Gibbs was quite conscious in using entropy as a basic variable. His derivation of many important results in thermodynamics seems effortless. The use of entropy as a basic variable in economic theory has similar benefits.

The following graph is the Carnot cycle on a Temperature-Entropy diagram. Compared with the graph on a Pressure-Volume diagram, you can see how simple it is.