  We propose the use of a gravitational uncertainty principle for gravitation.
We define the corresponding gravitational Planck's constant and the
gravitational quantum of mass. We define entropy in terms of the quantum of
gravity with the property of having an extensive quality. The equivalent 2nd
law of thermodynamics is derived, the entropy increasing linearly with
cosmological time. These concepts are applied to the case of black holes,
finding their entropy and discussing their radiation.
