The Matter-Gravity Entanglement Hypothesis
Abstract
I outline some of my work and results (some dating back to 1998, some more recent) on my matter-gravity entanglement hypothesis, according to which the entropy of a closed quantum gravitational system is equal to the system's matter-gravity entanglement entropy. The main arguments presented are: (1) that this hypothesis is capable of resolving what I call the second-law puzzle, i.e. the puzzle as to how the entropy increase of a closed system can be reconciled with the asssumption of unitary time-evolution; (2) that the black hole information loss puzzle may be regarded as a special case of this second law puzzle and that therefore the same resolution applies to it; (3) that the black hole thermal atmosphere puzzle (which I recall) can be resolved by adopting a radically different-from-usual description of quantum black hole equilibrium states, according to which they are total pure states, entangled between matter and gravity in such a way that the partial states of matter and gravity are each approximately thermal equilibrium states (at the Hawking temperature); (4) that the Susskind-Horowitz-Polchinski string-theoretic understanding of black hole entropy as the logarithm of the degeneracy of a long string (which is the weak string coupling limit of a black hole) cannot be quite correct but should be replaced by a modified understanding according to which it is the entanglement entropy between a long string and its stringy atmosphere, when in a total pure equilibrium state in a suitable box, which (in line with (3)) goes over, at strong-coupling, to a black hole in equilibrium with its thermal atmosphere. The modified understanding in (4) is based on a general result, which I also describe, which concerns the likely state of a quantum system when it is weakly coupled to an energy-bath and the total state is a random pure state with a given energy. This result generalizes Goldstein et al.'s `canonical typicality' result to systems which are not necessarily small.
- Publication:
-
Foundations of Physics
- Pub Date:
- May 2018
- DOI:
- 10.1007/s10701-018-0150-7
- arXiv:
- arXiv:1802.03635
- Bibcode:
- 2018FoPh...48..542K
- Keywords:
-
- Matter-gravity entanglement;
- Information loss;
- String theory approach to black hole entropy;
- Gravitational decoherence;
- Second law of thermodynamics;
- Canonical typicality;
- High Energy Physics - Theory;
- Condensed Matter - Statistical Mechanics;
- General Relativity and Quantum Cosmology;
- Quantum Physics
- E-Print:
- 17 pages, 11 figures. Written version of talk given at 18th UK and European Conference on Foundations of Physics (16-18 July 2016, LSE, London, UK). To appear in 'Foundations of Physics' Special Issue entitled "Philosophical Aspects in the Foundations of Physics" (Guest editors: Harvey Brown, Klaas Landsman, Miklos Redei.) v2: Minor corrections, v3:Improved wording in a few places