Gravitational EntropyAccording to its primary formulator Stephen Hawking, gravitational entropy is "a measure of what we can't know" about the universe, and involves the loss of information to black holes and an extension of the definition of entropy itself as an effect of the gravitational field (extraction of time as a residue of gravitational annihilation - topology-shaping - of space).
In 1975 Hawking and Jacob Beckenstein demonstrated that black holes emit radiation (known as Hawking Radiation) from virtual particle pair production near the event horizon. The effect would be significant for very small black holes - and quantum black holes - but would not be observed in cosmic black holes that are constantly annihilating matter and consuming energy in far greater amounts than could be radiated from this virtual process.
It is the matter and energy consumed from the black hole's surroundings that represents information being lost - a violation of conservation laws unless at the end time of the universe Hawking Radiation returns the information and shrinks the end-time holes to zero.
Gravitational entropy is given by the horizon area in Planck units and is not localized, but must be defined globally per General Relativity in all 4 or 5-dimensional black holes.
Web Resources On Gravitational Entropy
Physics Colloquiums - Gravitational Entropy
Hawking Radiation
A measure of gravitational entropy and structure formation
Book Resources On Gravitational EntropyEntropy (Princeton Series in Applied Mathematics) by Andreas Greven, Gerhard Keller and Gerald Warnecke, Eds.
The Einstein Equations and the Large Scale Behavior of Gravitational Fields: 50 Years of the Cauchy Problem in General Relativity by Piotr T. Chrusciel and Helmut Friedrich, Eds.
The Nature of Space and Time by Stephen Hawking and Roger Penrose
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