Austrian physicist who established the relationship between entropy and the statistical analysis of molecular motion in 1877, founding the branch of physics known as statistical mechanics. Boltzmann's statistical interpretation led him to conclude that entropy -decreasing processes were exceedingly improbable but not absolutely impossible. It also paved the way for the development of quantum mechanics, which is inherently a statistical theory. Boltzmann argued that the equipartition theorem was a fundamental feature of the kinetic theory. He also derived the "H-theorem " and Boltzmann equation in his paper of 1872. The H-theorem expresses the increase in entropy of an irreversible process.

Because of Boltzmann's dense and difficult style, his work was disseminated only after its exigesis by Ehrenfest in 1911. Boltzmann is buried in the Central Cemetery in Vienna. The equation , where S is entropy, k is Boltzmann's constant, stands for the natural logarithm, and W is the number of possible "states" of a system is written on Boltzmann's tombstone, although Planck was actually the first to write down the equation in this form.

Additional biographies: MacTutor (St. Andrews)