On Brane Cosmology and Naked Singularities

TL;DR

This paper investigates brane-world singularities, especially in supergravity contexts, showing they are quantum mechanically inconsistent and are typically shielded by a second boundary brane, resolving the singularity puzzle.

Contribution

It demonstrates the quantum inconsistency of brane-world naked singularities and reveals a topological obstruction that screens them off in supergravity models.

Findings

Time-like singularities are not wave-regular.

Null singularities absorb radiation.

Naked singularities are screened by a second boundary brane.

Abstract

Brane-world singularities are analysed, emphasizing the case of supergravity in singular spaces where the singularity puzzle is naturally resolved. These naked singularities are either time-like or null, corresponding to the finite or infinite amount of conformal time that massless particles take in order to reach them. Quantum mechanically we show that the brane-world naked singularities are inconsistent. Indeed we find that time-like singularities are not wave-regular, so the time-evolution of wave packets is not uniquely defined in their vicinity, while null singularities absorb incoming radiation. Finally we stress that for supergravity in singular spaces there is a topological obstruction, whereby naked singularities are necessarily screened off by the second boundary brane.