Geometric Backreaction of Modified Quantum Vacua and Diffeomorphisim Covariance

TL;DR

This paper demonstrates that modified quantum vacua influence background geometry, leading to effective spacetime structures similar to (anti) de Sitter space, which can explain superluminal photon propagation without violating causality or covariance.

Contribution

It provides a semi-classical geometric framework showing how quantum vacuum modifications affect spacetime structure and photon propagation.

Findings

Modified vacua induce (anti) de Sitter-like geometries.

Photon superluminality explained by geometric effects.

Causality preserved despite superluminal effects.

Abstract

In this paper we have shown that squeezed modified quantum vacua have an effect on the background geometry by solving the semi-classical Einstein Field Equations in modified vacuum. The resultant geometry is similar to (anti) de Sitter spacetime. This geometry could explain the change of causal structure - speed of light- in such vacua without violating diffeomorphism covariance or causality.The superluminal propagation of photons in Casimir vacuum is deduced from the effective electromagnetic action in the resultant curved geometry. Singling between different vacua is shown not to violate causality as well when the geometric effect on the null rays is considered, causing a refraction of those rays when travelling between unbounded and modified vacua.