Lessons of Quantum 2D Dilaton Gravity

TL;DR

This paper argues that semiclassical equations in 2D dilaton gravity should be viewed as WKB trajectories rather than expectation values, challenging the notion of quantum information loss in black hole evaporation.

Contribution

It provides a new interpretation of semiclassical equations in 2D dilaton gravity, emphasizing their WKB nature over quantum expectation values.

Findings

Semiclassical equations are better understood as WKB trajectories.

Quantum information loss may not be well-defined at the semiclassical level.

Challenges the standard interpretation of black hole evaporation in quantum gravity.

Abstract

Based on the analysis of two dimensional dilaton gravity we argue that the semiclassical equations of black hole formation and evaporation should not be interpreted in terms of expectation values of operators in the exact quantum theory, but rather as WKB trajectories. Thus at the semiclassical level it does not seem possible to formulate a notion of {\it quantum mechanical} information loss.