Used with
permission of Maiken Naylor, University at Buffalo, Buffalo, NY, USA,
http://ublib.buffalo.edu/libraries/units/sel/exhibits/stamps
The Austrian physicist Ludwig Boltzmann (1844-1906) developed and advanced the theories of thermodynamics, the kinetic theory of gases, and electromagnetism at a time when new discoveries about the structure of matter were being made. Boltzmann supposed that the behavior of gases depended on the movement of their atoms or molecules. From a consideration of the second law of thermodynamics he arrived at a mathematical formulation of the fact that equilibrium is the most probable state for a gas to achieve. As expressed by his famous equation, entropy is proportional to the log of probability: the Boltzmann constant, k, is named after him. The Nicaraguan stamp features an internal combustion engine as an application of kinetic theory. Boltzmann is also commemorated on the Austrian stamp bearing his likeness.