Effective dynamics of Janis-Newman-Winicour spacetime

TL;DR

This paper investigates quantum-corrected effective dynamics of the Janis-Newman-Winicour spacetime inspired by loop quantum gravity, demonstrating singularity resolution via quantum bounces in one scheme but not in another.

Contribution

It introduces two schemes for regularizing the Hamiltonian constraint and analyzes their implications for the effective spacetime structure.

Findings

Quantum bounces resolve singularities in the $$ scheme.

Effective spacetime extends previous models with quantum corrections.

The Dirac observable scheme encounters singularities due to zero points.

Abstract

The effective dynamics of the Janis-Newman-Winicour spacetime inspired by loop quantum gravity is studied. Two different schemes are considered to regularize the Hamiltonian constraint for the quantum dynamics. In the $\mu_0$ scheme in which the quantum parameters are treated as constants, the equations of motion generated by the effective Hamiltonian are solved analytically. The resulting quantum-corrected effective spacetime obviously extends the effective spacetime previously obtained in the literature. In the new effective spacetime, the naked singularity and the central singularity presented in the classical JNW spacetime are resolved by a series of quantum bounces. In the scheme of choosing the quantum parameters as Dirac observables, the effective dynamics is also solved in the light of the solution in $\mu_0$ scheme. It turns out that the resulting effective spacetime has singularities due to the appearance of the zero points of the time reparametrization functions. Hence, the effective theory in this scheme does not remain valid throughout the full spacetime.