CPT symmetry and antimatter gravity in general relativity

TL;DR

This paper explores the theoretical possibility that antimatter experiences gravitational repulsion from matter, suggesting that CPT symmetry in general relativity predicts antigravity, which could impact cosmological models of universe expansion.

Contribution

It demonstrates that CPT invariance implies antimatter may repel matter gravitationally within general relativity, a novel theoretical prediction.

Findings

CPT symmetry leads to a mutual repulsion between matter and antimatter in gravity.

Antigravity emerges as a prediction of general relativity under CPT transformation.

Supports cosmological models with matter-antimatter repulsion explaining universe acceleration.

Abstract

The gravitational behavior of antimatter is still unknown. While we may be confident that antimatter is self-attractive, the interaction between matter and antimatter might be either attractive or repulsive. We investigate this issue on theoretical grounds. Starting from the CPT invariance of physical laws, we transform matter into antimatter in the equations of both electrodynamics and gravitation. In the former case, the result is the well-known change of sign of the electric charge. In the latter, we find that the gravitational interaction between matter and antimatter is a mutual repulsion, i.e. antigravity appears as a prediction of general relativity when CPT is applied. This result supports cosmological models attempting to explain the Universe accelerated expansion in terms of a matter-antimatter repulsive interaction.