Negative energy and stability in scalar-tensor gravity

TL;DR

This paper investigates the stability of Minkowski space in scalar-tensor gravity theories, showing that despite negative energy in gravitational waves, the background remains classically stable under perturbations.

Contribution

It provides a gauge-invariant analysis demonstrating the classical stability of Minkowski space despite negative energy gravitational waves in scalar-tensor theories.

Findings

Linear gravitational waves carry negative energy in these theories.

Minkowski space is stable at the classical level under perturbations.

The analysis is gauge-invariant and applies to scalar and tensor modes.

Abstract

Linearized gravitational waves in Brans-Dicke and scalar-tensor theories carry negative energy. A gauge-invariant analysis shows that the background Minkowski space is stable at the classical level with respect to linear scalar and tensor inhomogeneous perturbations.