Violation of Bell inequalities from Cosmic Microwave Background data

TL;DR

This paper extends previous analyses of the Cosmic Microwave Background data to more precise WMAP and Planck datasets, finding a violation of Bell inequalities that challenges local realism in cosmology.

Contribution

It demonstrates that using current high-precision CMB data, a violation of Bell inequalities can be observed, supporting quantum origins of primordial fluctuations.

Findings

Violation of CHSH inequality found with WMAP and Planck data

Supports quantum mechanical explanation over local realism in cosmology

Extends previous negative results with less precise data

Abstract

In a recent paper [R. Dale. R. Lapiedra, and J. A. Morales-Lladosa, Phys. Rev. D {\bf 107}, 023506 (2023)] a cosmic-like Clauser-Horne-Shimony-Holt (CHSH) inequality was proved for the temperature fluctuations $\delta T$ of the perturbed Cosmic Microwave Background (CMB), assuming local realism. This inequality can be tested from observational data. In fact, no violation for it has been found from the CMB data provided by the COBE satellite in different sky directions. This is a result which, being negative, is not conclusive in relation to the possible violation of the CHSH inequality in a cosmological context. So, the preceding analysis needs to be extended by using more precise current CMB data, like those provided by WMAP and Planck satellites. This is a task of considerable importance but, technically, much more involved in data treatments. In this work, assuming again local realism behind measurements and observational data, this extension is accomplished. The result is that a sound violation of the CHSH inequality is found, which would mean the failure of the assumed local realism in accordance with the quantum origin of the primordial temperature fluctuations in the framework of standard inflation and the orthodox interpretation of the Quantum Mechanics.