Expanding and contracting universes in third quantized string cosmology

TL;DR

This paper explores quantum transitions in string cosmology, proposing mechanisms for universe creation and contraction through third quantization and wave function anti-tunnelling, highlighting novel universe pair production processes.

Contribution

It introduces a third-quantization framework to describe universe pair creation and quantum transitions in string cosmology with contracting universes.

Findings

Quantum transitions can be modeled as anti-tunnelling in Wheeler--De Witt wave functions.

Universe pair production occurs from the string perturbative vacuum.

Transitions depend on the dilaton potential preserving the Hubble factor sign.

Abstract

We discuss the possibility of quantum transitions from the string perturbative vacuum to cosmological configurations characterized by isotropic contraction and decreasing dilaton. When the dilaton potential preserves the sign of the Hubble factor throughout the evolution, such transitions can be represented as an anti-tunnelling of the Wheeler--De Witt wave function in minisuperspace or, in a third-quantization language, as the production of pairs of universes out of the vacuum.