Abstract:
A concise survey of the black hole information paradox and its current status is given. A summary is also given of recent arguments against remnants. The assumptions underlying remnants, namely unitarity and causality, would imply that Reissner Nordstrom black holes have infinite internal states. These can be argued to lead to an unacceptable infinite production rate of such black holes in background fields. (To appear in the proceedings of the PASCOS symposium/Johns Hopkins Workshop, Baltimore, MD, March 22-25, 1995).

Abstract:
After a brief reminscence about work with K. Sato 25 years ago on the monopole problem and inflation, a discussion is given of the black hole information paradox. It is argued that, quite generally, it should be anticipated that the states behind a horizon should be correlated with states outside the horizon, and that this quantum mechanical entanglement is the key to understanding unitarity in this context. This should be equally true of cosmologies with horizons, such as de Sitter space, or of eternal black holes, or of black holes formed by gravitational collapse.

Abstract:
We propose a combination of two mechanisms that can resolve the black hole information paradox. The first process is that the black hole shrinks by a first order transition, since we assume the entropy is discontinuous. The black hole disappears. The second type of processes conserves unitarity. We assume that within the black hole micro-reversible quantum mechanical processes take place. These are ordinary particle processes, e.g. the decay of an electron and a positron into two photons.

Abstract:
Semiclassical reasoning suggests that the process by which an object collapses into a black hole and then evaporates by emitting Hawking radiation may destroy information, a problem often referred to as the black hole information paradox. Further, there seems to be no unique prediction of where the information about the collapsing body is localized. We propose that the latter aspect of the paradox may be a manifestation of an inconsistent self-reference in the semiclassical theory of black hole evolution. This suggests the inadequacy of the semiclassical approach or, at worst, that standard quantum mechanics and general relavity are fundamentally incompatible. One option for the resolution for the paradox in the localization is to identify the G\"odel-like incompleteness that corresponds to an imposition of consistency, and introduce possibly new physics that supplies this incompleteness. Another option is to modify the theory in such a way as to prohibit self-reference. We discuss various possible scenarios to implement these options, including eternally collapsing objects, black hole remnants, black hole final states, and simple variants of semiclassical quantum gravity.

Abstract:
The black hole information paradox is the result of contradiction between Hawking's semi-classical argument, which dictates that the quantum coherence should be lost during the black hole evaporation and the fundamental principles of quantum mechanics, the evolution of pure states to pure states. For over three decades, this contradiction has been one of the major obstacles to the ultimate unification of quantum mechanics and general relativity. Recently, a final-state boundary condition inside the black hole was proposed to resolve this contradiction for bosons. However, no such a remedy exists for fermions yet even though Hawking effect for fermions has been studied for sometime. Here, I report that the black hole information paradox can be resolved for the fermions by imposing a final state boundary condition, which resembles local measurement with post selection. In this scenario, the evaporation can be seen as the post selection determined by random unitary transformation. It is also found that the evaporation processes strongly depends on the boundary condition at the event horizon. This approach may pave the way towards the unified theory for the resolution of information paradox and beyond.

The information paradox first surfaced in the early 1970s when Stephen
Hawking of Cambridge University suggested that black holes are not totally
black. Hawking showed that particle-antiparticle pairs generated at the event
horizon—the outer periphery of a black hole—would be separated. One particle
would fall into the black hole while the other would escape, making the black
hole a radiating body. Characteristics of the emission and absorption of usual
substance by a black hole can be described by information models. Estimation of
the volume of information in black holes is necessary for generation of
restrictions for their formation, development and interconversion. Information
is an integral part of the Universe. By its physical essence information is heterogeneity of matter and
energy. Therefore information is inseparably connected with matter and
energy. An information approach along with a physical one allows to obtain new,
sometimes more general data in relation to data obtained on the ground of physical
rules only. The author’s works, testify about the practicality of information
laws usage simultaneously with physical rules for cognition of the Universe.
The results presented in this paper show the effectiveness of informational
approach for studying the black holes. The article discusses the following
questions: The volume of information in the black hole; Information model of a
black hole; Characteristics of the emission and absorption of usual substance
by a black hole describes the information model of a black hole; The
information paradox; A simple explanation of the information paradox by the information
model of a black hole.

Abstract:
Near-extremal black holes are obtained by exciting the Ramond sector of the D1-D5 CFT, where the ground state is highly degenerate. We find that the dual geometries for these ground states have throats that end in a way that is characterized by the CFT state. Below the black hole threshold we find a detailed agreement between propagation in the throat and excitations of the CFT. We study the breakdown of the semiclassical approximation and relate the results to the proposal of gr-qc/0007011 for resolving the information paradox: semiclassical evolution breaks down if hypersurfaces stretch too much during an evolution. We find that a volume V stretches to a maximum throat depth of V/2G.

Abstract:
The recent progress in string theory strongly suggests that formation and evaporation of black holes is a unitary process. This fact makes it imperative that we find a flaw in the semiclassical reasoning that implies a loss of information. We propose a new criterion that limits the domain of classical gravity: the hypersurfaces of a foliation cannot be stretched too much. This conjectured criterion may have important consequences for the early Universe.

Abstract:
The conservative model of a black hole is advanced. The model incorporates conservation laws such as those of baryon and lepton numbers, which lifts the information loss paradox. A scenario of black hole evaporation is considered. Keywords: entropy, emission, radiation, universe, chemical potential