Information Retrieval from Black Holes

  • Sumanta ChakrabortyEmail author
Part of the Springer Theses book series (Springer Theses)


It is generally believed that, a black hole, originating from collapse of matter, erases all the information about the initial state. In other words, the initial configuration of matter forming a black hole cannot be retrieved by future asymptotic observers, through local measurements. This is in sharp contrast with the expectation from a unitary evolution in quantum theory and leads to (a version of) the black hole information paradox. Classically, no-hair theorems guarantee that, apart from mass, charge and angular momentum, nothing is expected to be revealed to such asymptotic observers after the formation of a black hole. On the other hand, semi-classically, black holes evaporate after their formation through the emission of Hawking radiation. The dominant part of the radiation is expected to be thermal and hence one cannot have any knowledge about the initial data. However, there can be distortions in the Hawking radiation from thermality, which even though not strong enough to make the evolution unitary, do carry some part of information regarding the in-state. In this chapter, we show how one may decipher the information about the in-state of the field from such distortions. In particular, distortions of a particular kind can be used to reconstruct the initial data completely.


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Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  1. 1.Department of Theoretical PhysicsIndian Association for the Cultivation of ScienceJadavpur, KolkataIndia

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