Entropic force
In physics, an entropic force acting in a system is an emergent phenomenon resulting from the entire system's statistical tendency to increase its entropy, rather than from a particular underlying force on the atomic scale. == Mathematical formulation == In the canonical ensemble, the entropic force F {\displaystyle \mathbf {F} } associated to a macrostate partition { X } {\displaystyle \{\mathbf {X} \}} is given by F ( X 0 ) = T ∇ X S ( X ) | X 0 , {\displaystyle \mathbf {F} (\mathbf {X} _{0})=T\nabla _{\mathbf {X} }S(\mathbf {X} )|_{\mathbf {X} _{0}},} where T {\displaystyle T} is the temperature, S ( X ) {\displaystyle S(\mathbf {X} )} is the entropy associated to the macrostate X {\displaystyle \mathbf {X} } , and X 0 {\displaystyle \mathbf {X} _{0}} is the present macrostate.