Finite-Range Gravity and Its Role in Gravitational Waves, Black Holes and Cosmology

TL;DR

This paper explores finite-range modifications of general relativity through massive gravity theories, showing they are consistent with experiments and can alter black hole and cosmological behaviors, including eliminating horizons and enabling accelerated expansion.

Contribution

It introduces a fully consistent finite-range gravity theory with specific mass terms, contrasting with Fierz-Pauli theory, and analyzes its implications for black holes and cosmology.

Findings

Finite-range gravity eliminates black hole event horizons.

The theory predicts oscillatory universe expansion.

Some variants allow accelerated cosmic expansion.

Abstract

Theoretical considerations of fundamental physics, as well as certain cosmological observations, persistently point out to permissibility, and maybe necessity, of macroscopic modifications of the Einstein general relativity. The field-theoretical formulation of general relativity helped us to identify the phenomenological seeds of such modifications. They take place in the form of very specific mass-terms, which appear in addition to the field-theoretical analog of the usual Hilbert-Einstein Lagrangian. We interpret the added terms as masses of the spin-2 and spin-0 gravitons. The arising finite-range gravity is a fully consistent theory, which smoothly approaches general relativity in the massless limit, that is, when both masses tend to zero and the range of gravity tends to infinity. We show that all local weak-field predictions of the theory are in perfect agreement with the available experimental data. However, some other conclusions of the non-linear massive theory are in a striking contrast with those of general relativity. We show in detail how the arbitrarily small mass-terms eliminate the black hole event horizon and replace a permanent power-law expansion of a homogeneous isotropic universe with an oscillatory behaviour. One variant of the theory allows the cosmological scale factor to exhibit an `accelerated expansion'instead of slowing down to a regular maximum of expansion. We show in detail why the traditional, Fierz-Pauli, massive gravity is in conflict not only with the static-field experiments but also with the available indirect gravitational-wave observations. At the same time, we demonstrate the incorrectness of the widely held belief that the non-Fierz-Pauli theories possess `negative energies' and `instabilities'.