One form of this quantity
One form of this quantity is given as a trace of a function of the density matrix. The elasticity of rubber is driven by the configurational type of this quantity,  and Bekenstein showed that a black hole has a maximal value of this quantity for a given volume. This quantity is proposed to reach an absolute maximum in the heat death of the universe. A common form of this quantity is given by Boltzmann's constant times  the natural logarithm of the number of microstates while it can be calculated for simple systems by integrating dQ over T. FTP, name this quantity commonly described as the amount of chaos in a system, which is always increasing according to the 2nd law of Thermodynamics.
One form of this quantity is given as a trace of a function of the density matrix.
Entropy