The Extended Equivalence Principle and the Kramers-Kronig Relations

TL;DR

This paper examines an extended version of the equivalence principle in gravity, using Kramers-Kronig relations, and concludes that observational evidence contradicts this extended principle.

Contribution

It introduces a novel analysis linking the extended equivalence principle with dispersion relations, showing observational violations of the extended principle.

Findings

Observational facts conflict with the extended equivalence principle.

Kramers-Kronig relations imply violations of composition-independent response.

The extended principle cannot hold universally in light of known data.

Abstract

A seemingly obvious extension of the weak equivalence principle, in which all matter must respond to Post-Newtonian gravitational fields, such as Lense-Thirring and radiation fields, in a composition-independent way, is considered in light of the Kramers-Kronig dispersion relations for the linear response of any material medium to these fields. It is argued that known observational facts lead to violations of this extended form of the equivalence principle. (PACS numbers: 04.80.Cc, 04.80.Nn, 03.65.Ud, 67.40.Bz)