# Phantom singularities and their quantum fate: general relativity and beyond

## TL;DR

This paper reviews the nature of phantom singularities in cosmology, explores their potential avoidance through quantum gravity, and discusses alternative theories mimicking phantom behavior.

## Contribution

It provides a comprehensive overview of phantom singularities, their types, and how quantum cosmology might prevent these singularities, including the role of alternative gravity theories.

## Key findings

- Phantom singularities can potentially be avoided in quantum cosmology.
- Alternative gravity theories can mimic phantom energy behavior.
- Quantum effects may resolve classical singularities.

## Abstract

Cosmological observations allow the possibility that dark energy is caused by phantom fields. These fields typically lead to the occurrence of singularities in the late Universe. We review here the status of phantom singularities and their possible avoidance in a quantum theory of gravity. We first introduce phantom energy and discuss its behavior in cosmology. We then list the various types of singularities that can occur from its presence. We also discuss the possibility that phantom behavior is mimicked by an alternative theory of gravity. We finally address the quantum cosmology of these models and discuss in which sense the phantom singularities can be avoided.