The
study of the
movement of
heat from
one body to
another and the
reactions
between heat and
other forms of
energy.
See: The Three Laws of Thermodynamics
Thermodynamics studies the dynamics of heat, or the flow, production, and conversion of heat energy into work.
It arose from the study of the steam engine and other "heat engines" that convert heat into mechanical work. The results of that work have effected branches of philosophy.