Thermodynamics
1708.jpg")
![The thermodynamicists representative of the original eight founding schools of thermodynamics. The schools with the most-lasting effect in founding the modern versions of thermodynamics are the Berlin school, particularly as established in Rudolf Clausius's 1865 textbook The Mechanical Theory of Heat, the Vienna school, while the statistical mechanics of Ludwig Boltzmann, and the Gibbsian school at Yale University, led by the American engineer Willard Gibbs' 1876 On the Equilibrium of Heterogeneous Substances launched chemical thermodynamics.](/Images/godic/202412/21/Eight_founding_schools1708.png")
![The lifetimes of some of the most important contributors to thermodynamics](/Images/godic/202412/21/Thermodynamics1709.png")
![A diagram of a generic thermodynamic system](/Images/godic/202412/21/System_boundary.svg1709.png")
Thermodynamics is a branch of physics concerned with heat and temperature and their relation to energy and work. It defines macroscopic variables, such as internal energy, entropy, and pressure, that partly describe a body of matter or radiation. It states that the behavior of those variables is subject to general constraints, that are common to all materials, beyond the peculiar properties of particular materials. These general constraints are expressed in the four laws of thermodynamics. Thermodynamics describes the bulk behavior of the body, not the microscopic behaviors of the very large numbers of its microscopic constituents, such as molecules. The basic results of thermodynamics rely on the existence of idealized states of thermodynamic equilibrium. Its laws are explained by statistical mechanics, in terms of the microscopic constituents.