Inflation and Dirac in the Causal Set Approach to Discrete Quantum Gravity

TL;DR

This paper presents a causal set approach to discrete quantum gravity, describing universe evolution, inflation, multiverse divergence, and introduces a discrete Dirac operator with implications for multiverse probabilities.

Contribution

It introduces a novel causal set model incorporating inflation, multiverse divergence, and a discrete Dirac operator, linking quantum mechanics with discrete gravity.

Findings

Identification of a common inflationary period across universes

Emergence of a four-dimensional discrete manifold in the multiverse phase

Predictions of pulsating universe dominance based on coupling constants

Abstract

In this approach to discrete quantum gravity the basic structural element is a covariant causal set ($c$-causet). The geometry of a $c$-causet is described by a shell-sequence that determines the discrete gravity of a universe. In this growth model, universes evolve in discrete time by adding new vertices to their generating $c$-causet. We first describe an inflationary period that is common to all universes. After this very brief cycle, the model enters a multiverse period in which the system diverges in various ways forming paths of $c$-causets. At the beginning of the multiverse period, the structure of a four-dimensional discrete manifold emerges and quantum mechanics enters the picture. A natural Hilbert space is defined and a discrete, free Dirac operator is introduced. We determine the eigenvalues and eigenvectors of this operator. Finally, we propose values for coupling constants that determine multiverse probabilities. These probabilities predict the dominance of pulsating universes.