Observational Exclusion of a Consistent Quantum Cosmology Scenario

TL;DR

This paper tests a specific quantum cosmology model predicting inflation against recent cosmic microwave background data and finds it incompatible across all parameters, challenging its viability.

Contribution

It provides the first observational exclusion of a well-motivated quantum cosmology model predicting inflation, demonstrating its falsifiability.

Findings

Model is excluded by current B-mode observations

No parameter tuning can reconcile the model with data

Implications for loop quantum cosmology's testability

Abstract

It is often argued that inflation erases all the information about what took place before it started. Quantum gravity, relevant in the Planck era, seems therefore mostly impossible to probe with cosmological observations. In general, only very ad hoc scenarios or hyper fine-tuned initial conditions can lead to observationally testable theories. Here we consider a well-defined and well motivated candidate quantum cosmology model that predicts inflation. Using the most recent observational constraints on the cosmic microwave background B modes, we show that the model is excluded for all its parameter space, without any tuning. Some important consequences are drawn for the deformed algebra approach to loop quantum cosmology. We emphasize that neither loop quantum cosmology in general nor loop quantum gravity are disfavored by this study but their falsifiability is established.