 # Statistical Mechanics

Statistical mechanics can be considered as one of the pillars of modern physics. It is useful in the fundamental study of the physical system with a large number of degree of freedom. The approach is usually based on probability theory, statistical methods and microscopic physical laws. In this short piece of article, we will be discussing more statistical mechanics and statistical thermodynamics, a branch that extends and treats classical thermodynamics.

## What is Statistical Mechanics?

Statistical mechanics is the branch of the theory of physics, studying the use of probability theory and also the Average or mean behaviour of a mechanical system wherein the state of the system is said to be uncertain. The common use of this mechanics is in the thermodynamic accomplishment of large systems. The statistical thermodynamics or the statistical mechanics are the branches of statistical mechanics.

The advantage of using this mechanics is to provide exact methods of connecting the thermodynamic quantities to the microscopic behaviour. The statistical form of mechanics also makes possible in extending the laws of thermodynamics with few or some degrees of freedom.

## Statistical Thermodynamics

The statistical thermodynamics helps in the derivation of the classical thermodynamics of various materials coming in terms of the property of the constituent particles and also interaction between them. In simple ways, statistical thermodynamics gives a connection between macroscopic properties of the materials coming in thermodynamic equilibrium and also the microscopic behaviour as well as the motions that occur inside the material. Whereas the statistical mechanics involves dynamics and is mainly focused on the statistical equilibrium.

### Non-equilibrium

There are a various physical phenomenon of interest which involves quasi-thermodynamic processes of equilibrium, here are some of the examples

• The transport of heat by internal motions within a material, is driven by an imbalance in the temperature.
• The Electric currents that are carried by motion of the charges in a conductor, is well driven by an imbalance in the voltage.
• A Spontaneous chemical reaction is driven by the decrease in free energy.
• Friction, quantum decoherence & dissipation.
• Systems that are being pumped by the external forces.
• In general, an Irreversible process

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