Geometrogenesis under Quantum Graphity: problems with the ripening Universe

TL;DR

This paper investigates the Quantum Graphity model of emergent geometry, demonstrating that the original formulation favors disconnected graphs, and introduces a hypervalence term to promote a connected, lattice-like structure resembling our universe.

Contribution

The paper identifies a limitation in the original Quantum Graphity model and proposes a new hypervalence term to favor connected, universe-like geometries.

Findings

Original QG favors disconnected subgraphs.

Hypervalence term promotes connected, lattice-like graphs.

Connected graphs better represent our universe.

Abstract

Quantum Graphity (QG) is a model of emergent geometry in which space is represented by a dynamical graph. The graph evolves under the action of a Hamiltonian from a high-energy pre-geometric state to a low-energy state in which geometry emerges as a coarse-grained effective property of space. Here we show the results of numerical modelling of the evolution of the QG Hamiltonian, a process we term "ripening" by analogy with crystallographic growth. We find that the model as originally presented favours a graph composed of small disjoint subgraphs. Such a disconnected space is a poor representation of our universe. A new term is introduced to the original QG Hamiltonian, which we call the hypervalence term. It is shown that the inclusion of a hypervalence term causes a connected lattice-like graph to be favoured over small isolated subgraphs.