2014/01/21 by Goffredo Chirco, Hal M. Haggard, Aldo Riello +1 · 2 citations
Physics and Astronomy · #gr-qc
paper · pdf · doi:10.1103/physrevd.90.044044
published as Phys. Rev. D 90, 044044 (2014) · 12 pages, 1 figure
arxiv created 2014/01/21 · arxiv updated 2014/08/20
A celebrated result by Jacobson is the derivation of Einstein's equations from Unruh's temperature, the Bekenstein-Hawking entropy and the Clausius relation. This has been repeatedly taken as evidence for an interpretation of Einstein's equations as equations of state for unknown degrees of freedom underlying the metric. We show that a different interpretation of Jacobson result is possible, which does not imply the existence of additional degrees of freedom, and follows only from the quantum properties of gravity. We introduce the notion of quantum gravitational Hadamard states, which give rise to the full local thermodynamics of gravity.