Quantum cosmology from the de Broglie-Bohm perspective

TL;DR

This paper reviews how the de Broglie-Bohm quantum theory applied to quantum cosmology can avoid initial singularities, explain isotropization, and predict observable effects, offering insights distinct from other quantum approaches.

Contribution

It demonstrates the application of the de Broglie-Bohm theory to quantum cosmology, including singularity avoidance, perturbation dynamics, and emergent structures of space and time.

Findings

Quantum effects can avoid the initial singularity.

Quantum cosmological perturbations have observable consequences.

De Broglie-Bohm approach provides unique insights not accessible by other theories.

Abstract

We review the main results that have been obtained in quantum cosmology from the perspective of the de Broglie-Bohm quantum theory. As it is a dynamical theory of assumed objectively real trajectories in the configuration space of the physical system under investigation, this quantum theory is not essentially probabilistic and dispenses the collapse postulate, turning it suitable to be applied to cosmology. In the framework of minisuperspace models, we show how quantum cosmological effects in the de-Broglie-Bohm's approach can avoid the initial singularity, and isotropize the Universe. We then extend minisuperspace in order to include linear cosmological perturbations. We present the main equations which govern the dynamics of quantum cosmological perturbations evolving in non-singular quantum cosmological backgrounds, and calculate some of their observational consequences. These results are not known how to be obtained in other approaches to quantum theory. In the general case of full superspace, we enumerate the possible structures of quantum space and time that emerge from the de Broglie-Bohm picture. Finally, we compare some of the results coming from the de Broglie-Bohm theory with other approaches, and discuss the physical reasons for some discrepancies that occur.