Serious limitations of the strong equivalence principle

TL;DR

This paper investigates the radiation emitted by accelerated neutral composite objects, revealing that their electromagnetic radiation depends on wavelength and structure, thereby challenging the universality of the strong equivalence principle.

Contribution

It demonstrates that decoherent radiation from neutral objects varies with wavelength and structure, highlighting limitations of the strong equivalence principle.

Findings

Long wavelength radiation is suppressed due to charge cancellation.

High energy, short wavelength radiation is emitted without suppression.

Gravitational radiation can surpass electromagnetic radiation at large orbital radii.

Abstract

It is well known that an accelerated charged particle radiates away energy. However, whether an accelerated neutral composite particle radiates away energy is unclear. We study decoherent Larmor radiation from an accelerated neutral composite object. We find that the neutral object's long wavelength radiation is highly suppressed because radiation from different charges is canceled out. However, the neutral object radiates high energy or short wavelength radiation without any suppression. In that case, radiation from each particle can be treated independently, and it is called the decoherent radiation. We compare a hydrogen atom's decoherent Larmor radiation with its gravitational radiation while the atom is in a circular orbit around a star. Gravitational radiation is stronger than the electromagnetic radiation if the orbital radius is larger than some critical radius. Since the decoherent radiation is related to the object's structure, this implies that the strong equivalence principle which states that gravitational motion does not depend on an object's constitution has severe limitations..