statistical mechanics

Statistical mechanics is a branch of physics that studies large-scale properties of matter based on the statistical laws of large numbers. The large numbers of molecules of such a system allows the use of statistics to predict the probability of finding the system in any state. The entropy (degree of disorder or randomness) of the system is related to the number of its possible states; a system left to itself will tend to approach the most probable distribution of energy states. See also thermodynamics.