Restoring predictability in semiclassical gravitational collapse

Ram Brustein, A. J.M. Medved

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


Hawking showed that the radiation emitted from a classical collapsing shell is thermal. Here, we show that a semiclassical collapsing shell emits radiation that is only approximately thermal, with small but significant deviations. The most important difference is the presence of small off-diagonal elements in the radiation density matrix with a magnitude of order 1 \√SBH, S BH being the Bekenstein-Hawking entropy of the incipient black hole. The off-diagonal elements store the correlations between the collapsing shell and the emitted radiation and allow information to continuously leak from the collapsed body. The rate of escape of information is initially very small, increasing to order one by the Page time, when the black hole has lost half its original entropy. We show that, until the Page time, the radiation is almost exactly thermal and that, from this time on, it begins to purify at an increasing rate.

Original languageEnglish
Article number15
JournalJournal of High Energy Physics
Issue number9
StatePublished - 1 Jan 2013


  • Black Holes
  • Models of Quantum Gravity

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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