Isotropic Loop Quantum Cosmology with Matter

TL;DR

This paper explores how coupling a massless scalar field to isotropic loop quantum cosmology removes singularities and modifies early universe behavior, providing a new perspective on initial conditions in quantum cosmology.

Contribution

It demonstrates how matter coupling in loop quantum cosmology regularizes singularities and generalizes initial conditions beyond classical limits.

Findings

Quantum model is non-singular near classical singularity.

Discrete structure regulates pathological behavior of matter Hamiltonians.

Dynamical initial conditions extend DeWitt's initial condition.

Abstract

A free massless scalar field is coupled to homogeneous and isotropic loop quantum cosmology. The coupled model is investigated in the vicinity of the classical singularity, where discreteness is essential and where the quantum model is non-singular, as well as in the regime of large volumes, where it displays the expected semiclassical features. The particular matter content (massless, free scalar) is chosen to illustrate how the discrete structure regulates pathological behavior caused by kinetic terms of matter Hamiltonians (which in standard quantum cosmology lead to wave functions with an infinite number of oscillations near the classical singularity). Due to this modification of the small volume behavior the dynamical initial conditions of loop quantum cosmology are seen to provide a meaningful generalization of DeWitt's initial condition.