Talk detail

Participant	Bianchi, Eugenio
Institution	Perimeter Institute for Theoretical Physics - 31 Caroline St. N. - Waterloo - Ontario - Canada

Session	QG4	Accepted		Order	Time
Talk	Oral abstract	Title	Entropy of Non-Extremal Black Holes from Loop Gravity
Co-authors
Abstract	We compute the thermodynamic entropy of non-extremal black holes using the quantum dynamics of Loop Gravity. The horizon entropy is finite, scales linearly with the area A, and reproduces the Bekenstein-Hawking expression S = A/4 with the one-fourth coefficient for all values of the Immirzi parameter. The near-horizon geometry of a non-extremal black hole - as seen by a stationary observer - is described by a Rindler horizon. We introduce the notion of a quantum Rindler horizon in the framework of Loop Gravity. The system is described by a quantum surface and the dynamics is generated by the boost Hamiltonion of Lorentzian Spinfoams. We show that the expectation value of the boost Hamiltonian reproduces the local horizon energy of Frodden, Ghosh and Perez. We study the coupling of the geometry of the quantum horizon to a two-level system and show that it thermalizes to the local Unruh temperature. The derived values of the energy and the temperature allow one to compute the thermodynamic entropy of the quantum horizon. The relation with the Spinfoam partition function is discussed.

Session	QG1	Accepted		Order	Time
Talk	Oral abstract	Title	Horizons in spin foam gravity
Co-authors
Abstract	Spin foams provide a formulation of loop quantum gravity in which local Lorentz invariance is a manifest symmetry of quantum space-time. I review progress in determining horizon boundary conditions in this approach, and discuss the thermal properties of the quantum horizon.