Quantum mechanics allows setting initial conditions at a cosmological singularity: Gowdy model example

TL;DR

This paper demonstrates that in a quantum cosmological model, initial conditions can be set directly at the singularity due to finite momenta, influencing graviton production during evolution.

Contribution

It shows that initial conditions at a cosmological singularity can be defined via quasi-Heisenberg quantization, a novel approach in quantum cosmology.

Findings

Initial momenta are finite at the singularity, enabling initial condition setting.

Wave packets can be constructed from finite momenta, avoiding divergence issues.

Some gravitons are produced during evolution, even with minimized late-time expansion.

Abstract

It is shown that the initial conditions in the quasi-Heisenberg quantization scheme can be set at the initial cosmological singularity per se. This possibility is provided by finiteness of some quantities, namely momentums of the dynamical variables, at a singularity, in spite of infinity of the dynamical variables themselves. The uncertainty principle allows avoiding a necessity to set values of the dynamical variables at singularity, as a wave packet can be expressed through the finite momentums. Influence of the initial condition set in the singularity in such a way to a number of gravitons under a vacuum state, arising during later evolution, is investigated. It is shown that, even choosing of some special state at the singularity minimizing late time expansion rate, some amount of gravitons still appear in the late time evolution.