Do We Live in an Antigravity Universe?

TL;DR

This paper explores a cosmological model where matter and antimatter repel gravitationally, leading to a universe with distinct properties such as fewer antistars, different expansion rates, and phenomena resembling MOND galaxy rotation curves.

Contribution

It introduces a novel antigravity universe model based on matter-antimatter gravitational repulsion and examines its consistency with cosmological observations.

Findings

Potential compatibility with ΛCDM parameters

Distinct cosmic acceleration and expansion features

Phenomenology including galaxy rotation and voids

Abstract

In arXiv:2401.10954 I showed that, in the context of antigravity (i.e., matter and antimatter repel gravitationally), quark/lepton mass-energy is matter and antiquark/antilepton mass-energy is antimatter while the mass-energy of the intermediate vector bosons (e.g., the photon and $W^+$) also has to be considered matter. One consequence of this is that the antiproton (and, hence, the antineutron) is dominantly composed of matter since some two-thirds of its mass is gluonic. Under this premise I found that the gravitational acceleration of antihydrogen would be $a_{\bar{H}}=(0.33^{+0.23}_{-0.11})g$. This is to be compared to the ALPHA-g result of $a_{\bar{H}}=(0.75\pm 0.13~({\rm stat.+syst.})\pm 0.16~({\rm simulation}))g$. In this article I explore the cosmological implications of this definition of matter and antimatter. This leads to a quite different antigravity universe than previous analyses with, for example, equal amounts of hydrogen and antihydrogen but far fewer antistars than stars. I examine the observations used to extract various parameters of the $\Lambda$CDM model of the universe and show that they are potentially consistent with the characteristics of the antigravity universe. A precise version of antigravity, one which must include General Relativity, is needed to generate a fully consistent, predictive model of the antigravity universe but even without it the antigravity scenario outlined here naturally leads to a rich phenomenology including different acceleration and expansion rates between the early universe and the present, MOND-like galaxy rotation curves, cosmic voids, and more.