Quantum geometric formulation of Brans-Dicke theory for Bianchi I spacetime

TL;DR

This paper extends loop quantum gravity techniques to Brans-Dicke Bianchi I spacetimes, demonstrating that quantum effects replace singularities with bounces and lead to a merging with classical spacetime.

Contribution

It introduces a quantum geometric formulation of Brans-Dicke theory for Bianchi I spacetime, analyzing singularity resolution and dynamics in this modified gravity context.

Findings

Classical singularities are replaced by quantum bounces.

All directional scale factors increase and reconnect with initial values after the bounce.

Quantum effects lead to a merging with classical spacetime post-bounce.

Abstract

This paper investigates Bianchi I spacetimes within the Jordan frame of Brans-Dicke theory, incorporating the framework of effective loop quantum gravity. After developing general formulas, we analyze the robustness of classical singularity resolution due to quantum geometric effects using two common quantization schemes. We then compare the resulting physical properties. We find that both schemes replace classical singularities with regular quantum bounces. Notably, in contrast to similar studies based on general relativity, we find that all three directional scale factors of the Bianchi I spacetimes increase and after the quantum bounce they reach values similar to their initial values, leading to a merging with classical spacetimes in both schemes.