Thermodynamics is a branch of physics that concerns the flow of heat energy and the ability to convert energy into work . (Work is also expressed as force x distance.). Thermodynamics is extensively used in chemistry, atmospheric science, geology and engineering.
Thermodynamics is part of a yet larger branch of physics called statistical mechanics, which bridges thermodynamics with modern physics. In fact, the discovery of quantum mechanics was an outcrop of thermodynamics. Josiah Williard Gibbs first utilized a quantum approach to express chemical reactions. Max Planck then utilized a quantum approach to express energy levels in photons being emitted from a hot object.
Motivation and Applications
An important motivation for development of thermodynamics as a discipline was to understand how to make engines more efficient, and what the maximum efficiency for engines could be. Another application was to express the energy involved in chemical reactions. Today, thermodynamics is useful for a wide range of applications from energy efficiency to economics.