Cosmic antigravity

TL;DR

This paper explores the concept of gravitational repulsion within General Relativity, discusses astronomical evidence for cosmic acceleration, and examines mechanisms and modifications of gravity that could explain the universe's accelerated expansion.

Contribution

It introduces the adjustment mechanism for vacuum energy and considers large-scale gravity modifications as potential explanations for cosmic acceleration.

Findings

Astronomical data support cosmological acceleration.

Adjustment mechanisms could resolve vacuum energy issues.

Modified gravity models may induce accelerated expansion.

Abstract

Possibility of gravitational repulsion in General Relativity is discussed and astronomical data in favor of cosmological acceleration are described. The problem of vacuum energy is emphasized and possible ways of its solution are indicated. The main attention is payed to adjustment mechanism which in principle could compensate originally huge vacuum energy down to cosmologically acceptable value and to solve the coincidence problem of a close magnitudes of the non-compensated remnants of vacuum energy and the energy density of the universe at the present time. Finally possible modifications of gravity at large scales which could induce accelerated cosmological expansion are considered.