Averaged null energy condition in Loop Quantum Cosmology

TL;DR

This paper investigates the averaged null energy condition in Loop Quantum Cosmology and finds that LQC violates this condition in a massless scalar field model, suggesting quantum effects can support exotic spacetime structures.

Contribution

It demonstrates that Loop Quantum Cosmology violates the averaged null energy condition in a specific scalar field model, linking quantum gravity effects to exotic spacetime phenomena.

Findings

LQC violates the averaged null energy condition in the studied model.

Quantum effects in LQC can support wormhole-like structures.

Supports the idea that quantum gravity modifies classical energy conditions.

Abstract

Wormhole and time machine are very interesting objects in general relativity. However, they need exotic matters which are impossible in classical level to support them. But if we introduce the quantum effects of gravity into the stress-energy tensor, these peculiar objects can be constructed self-consistently. Fortunately, loop quantum cosmology (LQC) has the potential to serve as a bridge connecting the classical theory and quantum gravity. Therefore it provides a simple way for the study of quantum effect in the semiclassical case. As is well known, loop quantum cosmology is very successful to deal with the behavior of early universe. In the early stage, if taken the quantum effect into consideration, inflation is natural because of the violation of every kind of local energy conditions. Similar to the inflationary universe, the violation of the averaged null energy condition is the necessary condition for the traversable wormholes. In this paper, we investigate the averaged null energy condition in LQC in the framework of effective Hamiltonian, and find out that LQC do violate the averaged null energy condition in the massless scalar field coupled model.