ABSTRACT
Statistical physics or statistical mechanics named as statistical thermodynamics in the case of equilibrium systems was originated in the work of Maxwell and Boltzmann on the kinetic theory of gases. To describe these systems, the concepts of quantum state and thermodynamic state are applied in statistical physics to develop a comprehensive methodology for the calculation of the parameters characterizing a thermodynamic state, for example, the functions characterizing a macroscopic system. As shown earlier all the needed information to calculate the thermodynamic properties of macroscopic systems is incorporated in the partition function or in the probability distribution function. An adequately small macroscopic particle immersed in a liquid shows a random type of motion called Brownian motion. In general, we designate the movement of a particle arising from thermal agitation by the Brownian motion, that is, the movement of small macroscopic particles, molecules, or atoms. Consequently, there is a diversity of significant physical phenomena that are essentially analogous to the Brownian motion.
