Gravity-induced vacuum dominance

TL;DR

This paper challenges the common belief that gravity's influence on quantum fields is always minor, demonstrating scenarios where vacuum energy density can dominate and significantly affect spacetime evolution, with potential astrophysical implications.

Contribution

It shows that under certain conditions, vacuum energy can become dominant due to spacetime evolution, contradicting previous assumptions of negligible gravitational effects on quantum fields.

Findings

Vacuum energy density can surpass classical energy densities in specific spacetime evolutions.

Infrared behavior of quantum fields influences vacuum dominance.

Potential astrophysical and cosmological impacts of vacuum dominance.

Abstract

It has been widely believed that, except in very extreme situations, the influence of gravity on quantum fields should amount to just small, sub-dominant contributions. This view seemed to be endorsed by the seminal results obtained over the last decades in the context of renormalization of quantum fields in curved spacetimes. Here, however, we argue that this belief is false by showing that there exist well-behaved spacetime evolutions where the vacuum energy density of free quantum fields is forced, by the very same background spacetime, to become dominant over any classical energy-density component. This semiclassical gravity effect finds its roots in the infrared behavior of fields on curved spacetimes. By estimating the time scale for the vacuum energy density to become dominant, and therefore for backreaction on the background spacetime to become important, we argue that this vacuum dominance may bear unexpected astrophysical and cosmological implications.