Austrian physicist and philosopher Ludwig Boltzmann was born #OTD in 1844.
His greatest achievements were the development of statistical mechanics, & the statistical explanation of the second law of thermodynamics. In 1877 he provided the current definition of entropy, S = kB ln Ω, where Ω is the number of microstates whose energy equals the system's energy, interpreted as a measure of statistical disorder of a system. Max Planck named the constant kB the Boltzmann constant.
