On the assumptions leading to the information loss paradox

TL;DR

This paper critically examines the assumptions behind the black hole information loss paradox, proposing that the paradox may stem from incompatible assumptions rather than actual information loss, and emphasizing the need for new physics before Planck scales.

Contribution

It offers a reformulation of the paradox by analyzing the assumptions leading to it, challenging the central dogma, and highlighting the potential compatibility of general relativity and quantum mechanics.

Findings

Incompatibility between classical relativity and the central dogma assumptions.

Standard arguments for the central dogma may not hold without new physics.

The paradox may not imply actual information loss, but rather a mismatch of assumptions.

Abstract

The information loss paradox is usually stated as an incompatibility between general relativity and quantum mechanics. However, the assumptions leading to the problem are often overlooked and, in fact, a careful inspection of the main hypothesises suggests a radical reformulation of the problem. Indeed, we present a thought experiment involving a black hole that emits radiation and, independently of the nature of the radiation, we show the existence of an incompatibility between (i) the validity of the laws of general relativity to describe infalling matter far from the Planckian regime, and (ii) the so-called central dogma which states that as seen from an outside observer a black hole behaves like a quantum system whose number of degrees of freedom is proportional to the horizon area. We critically revise the standard arguments in support of the central dogma, and argue that they cannot hold true unless some new physics is invoked even before reaching Planck scales. This suggests that the information loss problem, in its current formulation, is not necessarily related to any loss of information or lack of unitarity. Therefore, in principle, semiclassical general relativity and quantum mechanics can be perfectly compatible before reaching the final stage of the black hole evaporation where, instead, a consistent theory of quantum gravity is needed to make any prediction.