Entropic force

The entropic force results from the uniform probability distribution that exists spontaneously in all natural systems.

It represents the tendency to a more probable collection of states (macrostate) accompanied by a release of energy.

Its action is opposed by fundamental forces of attraction, such as the nuclear force, the electromagnetic attraction and the gravitational force.

Adiabatic transformations require that opposing the action of the entropic force be made with consumption of work done by other forces.

For example, adiabatic compression leads to heating because the action of compression forces opposes the dispersive action of the entropic force.

The magnetocaloric effect is another example. Magnetization is done by aligning all the dipoles in the same direction which leads to a decrease in entropy. This adiabatic magnetization also leads to heating.

The demagnetization is done by removing the external magnetic field which leads to the disalignment of the magnetic dipoles and this disalignment is done with the help of heat absorption, leading to cooling.

The extension of a rubber band makes all the polymer chains align in the same direction, leading to entropy decrease. This is accompanied by heating.

The relaxation of the rubber band makes the polymer chains entangle in a ball, the mutual orientation of the polymer chains varying. This entropy increase is accompanied by cooling because disalignment is done with the help of heat absorption.

The elasticity of rubber is an entropic force.