Can effects of quantum gravity be observed in the cosmic microwave background?

TL;DR

This paper explores whether quantum gravity effects can be detected in the cosmic microwave background anisotropies, finding potential suppression at large scales and setting bounds on inflation energy scales.

Contribution

It demonstrates how canonical quantum gravity can predict observable effects in the CMB, providing a framework to test quantum gravity theories.

Findings

Suppression of power at large scales in the CMB spectrum.

Current data sets an upper bound on inflation energy scale.

Framework applicable to other scenarios for observing quantum gravity effects.

Abstract

We investigate the question whether small quantum-gravitational effects can be observed in the anisotropy spectrum of the cosmic microwave background radiation. An observation of such an effect is needed in order to discriminate between different approaches to quantum gravity. Using canonical quantum gravity with the Wheeler-DeWitt equation, we find a suppression of power at large scales. Current observations only lead to an upper bound on the energy scale of inflation, but the framework is general enough to study other situations in which such effects might indeed be seen.