General Relativity and Gravitation

, Volume 28, Issue 11, pp 1293–1299 | Cite as

Physics with nonperturbative quantum gravity: Radiation from a quantum black hole

  • Marcelo Barreira
  • Mauro Carfora
  • Carlo Rovelli


We study quantum gravitational effects on black hole radiation, using loop quantum gravity. Bekenstein and Mukhanov have recently considered the modifications caused by quantum gravity on Hawking's thermal black-hole radiation. Using a simple ansatz for the eigenstates of the area, they have obtained the intriguing result that the quantum properties of geometry affect the radiation considerably, yielding a discrete spectrum, definitely non-thermal. Here, we replace the simple ansatz employed by Bekenstein and Mukhanov with the actual eigenstates of the area computed using loop quantum gravity. We derive the emission spectra, using a classic result in number theory by Hardy and Ramanujan. Disappointingly, we do not recover the Bekenstein-Mukhanov discrete spectrum, but — effectively — a continuum spectrum, consistent with Hawking's result. The Bekenstein-Mukhanov argument for the discreteness of the specrum is therefore likely to be an artifact of the ansatz, rather than a robust result (at least in its present kinematical version). The result is an example of concrete (although somewhat disappointing) application of nonperturbative quantum gravity.

Key words

Area eigenstates 


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Copyright information

© Plenum Publishing Corporation 1996

Authors and Affiliations

  • Marcelo Barreira
    • 1
  • Mauro Carfora
    • 2
  • Carlo Rovelli
    • 1
  1. 1.Department of Physics and AstronomyUniversity of PittsburghPittsburghUSA
  2. 2.SISSATriesteItaly

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