Primordial Black Holes: Tunnelling vs. No Boundary Proposal

TL;DR

This paper compares two quantum cosmology proposals, the no boundary and tunnelling proposals, in their predictions for primordial black hole formation during inflation, finding the no boundary approach consistent and the tunnelling approach unstable.

Contribution

It provides a calculation of black hole pair creation rates from the no boundary proposal and demonstrates the instability predicted by the tunnelling proposal.

Findings

No boundary proposal yields physically sensible black hole pair creation rates.

Tunnelling proposal predicts catastrophic instability of de Sitter space.

Results support the no boundary proposal over tunnelling for primordial black hole formation.

Abstract

In the inflationary era, black holes came into existence together with the universe through the quantum process of pair creation. We calculate the pair creation rate from the no boundary proposal for the wave function of the universe. Our results are physically sensible and fit in with other descriptions of pair creation. The tunnelling proposal, on the other hand, predicts a catastrophic instability of de Sitter space to the nucleation of large black holes, and cannot be maintained.