#### marcus

Science Advisor

Gold Member

Dearly Missed

- 24,650

- 781

http://arxiv.org/abs/1306.5206

Eugenio Bianchi, Hal M. Haggard, Carlo Rovelli

(Submitted on 21 Jun 2013)

We show that Oeckl's boundary formalism incorporates quantum statistical mechanics naturally, and we formulate general-covariant quantum statistical mechanics in this language. We illustrate the formalism by showing how it accounts for the Unruh effect. We observe that the distinction between pure and mixed states weakens in the general covariant context, and surmise that local gravitational processes are indivisibly statistical with no possible quantal versus probabilistic distinction.

8 pages, 2 figures

http://arxiv.org/abs/1306.4995

Viqar Husain, Tomasz Pawlowski

(Submitted on 20 Jun 2013)

We give a formulation of quantum cosmology with a pressureless dust and arbitrary additional matter fields. The dust provides a natural time gauge corresponding to a cosmic time, yielding a physical time independent Hamiltonian. The approach simplifies the analysis of both Wheeler-deWitt and loop quantum cosmology models, broadening the applicability of the latter.

3 pages. To appear in Proceedings of the 13th Marcel Grossmann Meeting (MG13), Stockholm, Sweden, 1-7 July 2012

brief mention:

http://arxiv.org/abs/1306.5063

Entropy from near-horizon geometries of Killing horizons

Olaf Dreyer, Amit Ghosh, Avirup Ghosh

(Submitted on 21 Jun 2013)

We derive black hole entropy based on the near-horizon symmetries of black hole space-times. To derive these symmetries we make use of an (R,T)-plane close to a Killing horizon. We identify a set of vector fields that preserves this plane and forms a Witt algebra. The corresponding algebra of Hamiltonians is shown to have a non-trivial central extension. Using the Cardy formula and the central charge we obtain the Bekenstein-Hawking entropy.

8 pages.

**The boundary is mixed**Eugenio Bianchi, Hal M. Haggard, Carlo Rovelli

(Submitted on 21 Jun 2013)

We show that Oeckl's boundary formalism incorporates quantum statistical mechanics naturally, and we formulate general-covariant quantum statistical mechanics in this language. We illustrate the formalism by showing how it accounts for the Unruh effect. We observe that the distinction between pure and mixed states weakens in the general covariant context, and surmise that local gravitational processes are indivisibly statistical with no possible quantal versus probabilistic distinction.

8 pages, 2 figures

http://arxiv.org/abs/1306.4995

**Dust time in quantum cosmology**Viqar Husain, Tomasz Pawlowski

(Submitted on 20 Jun 2013)

We give a formulation of quantum cosmology with a pressureless dust and arbitrary additional matter fields. The dust provides a natural time gauge corresponding to a cosmic time, yielding a physical time independent Hamiltonian. The approach simplifies the analysis of both Wheeler-deWitt and loop quantum cosmology models, broadening the applicability of the latter.

3 pages. To appear in Proceedings of the 13th Marcel Grossmann Meeting (MG13), Stockholm, Sweden, 1-7 July 2012

brief mention:

http://arxiv.org/abs/1306.5063

Entropy from near-horizon geometries of Killing horizons

Olaf Dreyer, Amit Ghosh, Avirup Ghosh

(Submitted on 21 Jun 2013)

We derive black hole entropy based on the near-horizon symmetries of black hole space-times. To derive these symmetries we make use of an (R,T)-plane close to a Killing horizon. We identify a set of vector fields that preserves this plane and forms a Witt algebra. The corresponding algebra of Hamiltonians is shown to have a non-trivial central extension. Using the Cardy formula and the central charge we obtain the Bekenstein-Hawking entropy.

8 pages.

Last edited: