Information is Not Lost in the Evaporation of 2D Black Holes

Abstract

We analyze Hawking evaporation of the Callan-Giddings-Harvey-Strominger black holes from a quantum geometry perspective and show that information is not lost, primarily because the quantum space-time is sufficiently larger than the classical. Using suitable approximations to extract physics from quantum space-times we establish that (i) the future null infinity of the quantum space-time is sufficiently long for the past vacuum to evolve to a pure state in the future, (ii) this state has a finite norm in the future Fock space, and (iii) all the information comes out at future infinity; there are no remnants.

Particle creation by loop black holes

“…However, if the singularity does not exist, this scenario cannot be correct. Since the singularity plays a central role for the causal spacetime diagram, its absence in the presence of quantum gravitational effects has consequences for the entire global structure [4], and its removal is essential for resolving the black hole information loss problem [5,6]. To understand the dynamics of the gravitational and matter fields, it is then necessary to have a concrete model.…”

“…An alternative resolution of the black hole singularity was obtained in an effective, noncommutative approach to quantum gravity [15] and in asymptotically safe quantum gravity [16]. In others works [6][17], a 2-dimensional model was used to study the evaporation process in the absence of a singularity. Recently also regular spinning loop black holes were obtained in [18].…”

Freely falling observer and black hole radiation

“…We do not have to postulate the complete evaporation of the black hole which plays an important role in the firewall argument [9]. It implies that the present argument has nothing to do with the remnant issue in [26,29]. On the other hand, it has also been claimed that there is no apparent need for firewalls because unitary evolution of black hole entangles a late mode located outside the horizon with a combination of early radiation and black hole states, instead of either of them separately [30].…”

Black hole evaporation: information loss but no paradox

“…the region which, in the classical characterization, would contain the singularity) would have to be a region with exotic properties, where, in all likelihood, the ordinary space-time notions would cease to be valid. Therefore, it is not completely clear how exactly, the information would traverse across such exotic region: In fact, in the 2 dimensional example based on the CGHS model presented in the work [17], the region corresponding to the "would be singularity" is replaced by a region where the conformal factor (which characterizes the space-time metric which is conformally flat), undergoes fluctuations about zero. That is, we have a region where the metric signature fluctuates 1 and, as far as we know, the evolution of a quantum field through such a region is not well understood (see [18] for a recent work discussing such problems in detail).…”