What is Entropy?

TL;DR

This book provides an elementary overview of entropy, covering fundamental concepts, calculations, and applications like hydrogen gas entropy, aimed at introducing entropy in thermodynamics and information theory.

Contribution

It offers a clear, accessible introduction to entropy concepts, calculations, and their interrelations, bridging thermodynamics and information theory.

Findings

Calculated entropy of hydrogen gas at standard conditions

Explained the relation between entropy, energy, and temperature

Illustrated entropy of classical systems like oscillators and gases

Abstract

This short book is an elementary course on entropy, leading up to a calculation of the entropy of hydrogen gas at standard temperature and pressure. Topics covered include information, Shannon entropy and Gibbs entropy, the principle of maximum entropy, the Boltzmann distribution, temperature and coolness, the relation between entropy, expected energy and temperature, the equipartition theorem, the partition function, the relation between expected energy, free energy and entropy, the entropy of a classical harmonic oscillator, the entropy of a classical particle in a box, and the entropy of a classical ideal gas.