In high school classes and even in Physics 001 here at Lehigh, I’ve heard the word entropy thrown around. Oh, entropy is a measure of disorder. Oh, entropy is always increasing. But the question that never seemed to be answered was the ever present, “so what?”
It wasn’t until I took thermodynamics this semester that I began to learn how to calculate the actual change in entropy of a system, and how calculating the entropy can help you find different state properties of the system, which is part of the state postulate.
For example, if given a piston-cylinder device, you can find the entropy change as a result of a change in temperature or pressure of whatever is in the piston-cylinder device. And while I’m still learning just what entropy is, it’s cool to start learning how the real world works.