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PIRSA:13040106

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https://pirsa.org/13040106

The imaginary part of the gravitational action and black hole entropy

Neiman, Y. (2013). The imaginary part of the gravitational action and black hole entropy. Perimeter Institute for Theoretical Physics. https://pirsa.org/13040106

Yasha Neiman Okinawa Institute of Science and Technology Graduate University

Talk numberPIRSA:13040106
DOI10.48660/13040106
Source RepositoryPIRSA
Collection
Talk Type Scientific Series
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Abstract

I present a candidate for a new derivation of black hole entropy. The key observation is that the action of General Relativity in bounded regions has an imaginary part, arising from the boundary term. The formula for this imaginary part is closely related to the Bekenstein-Hawking entropy formula, and coincides with it for certain classes of regions. This remains true in the presence of matter, and generalizes appropriately to Lovelock gravity. The imaginary part of the action is a versatile notion, requiring neither stationarity nor any knowledge about asymptotic infinity. Thus, it may provide a handle on quantum gravity in finite and dynamical regions. I derive the above results, make connections with standard approaches to black hole entropy, and speculate on the meaning of it all. Implications for loop quantum gravity are also discussed.