# Quantum Gravity from Causal Dynamical Triangulations: A Review

## TL;DR

This review summarizes recent advances in Causal Dynamical Triangulations (CDT), a lattice approach to quantum gravity, highlighting new insights into its phase structure, observables, and physical implications in four dimensions.

## Contribution

It provides a comprehensive overview of recent developments in CDT, emphasizing new results on phase structure, causality, and renormalization group applications.

## Key findings

- New phase structure insights in 4D CDT
- Role of causality and topology clarified
- Development of invariant quantum observables

## Abstract

This topical review gives a comprehensive overview and assessment of recent results in Causal Dynamical Triangulations (CDT), a modern formulation of lattice gravity, whose aim is to obtain a theory of quantum gravity nonperturbatively from a scaling limit of the lattice-regularized theory. In this manifestly diffeomorphism-invariant approach one has direct, computational access to a Planckian spacetime regime, which is explored with the help of invariant quantum observables. During the last few years, there have been numerous new and important developments and insights concerning the theory's phase structure, the roles of time, causality, diffeomorphisms and global topology, the application of renormalization group methods and new observables. We will focus on these new results, primarily in four spacetime dimensions, and discuss some of their geometric and physical implications.