# Can a negative-mass cosmology explain dark matter and dark energy?

## TL;DR

This paper critically reviews a negative-mass cosmology model that aims to unify dark matter and dark energy, highlighting significant observational and theoretical issues that challenge its viability.

## Contribution

It provides a detailed critique of Farnes's negative-mass cosmology, identifying key problems and discrepancies with observations and fundamental physics.

## Key findings

- Incorrect shape and density of galactic halos
- Halos would need to be less massive than baryonic matter
- Large-scale runaway effects would cause galaxies to move at near light speed

## Abstract

A recent study by Farnes (2018) proposed an alternative cosmological model in which both dark matter and dark energy are replaced with a single fluid of negative mass. This paper presents a critical review of that model. A number of problems and discrepancies with observations are identified. For instance, the predicted shape and density of galactic dark matter halos are incorrect. Also, halos would need to be less massive than the baryonic component otherwise they would become gravitationally unstable. Perhaps the most challenging problem in this theory is the presence of a large-scale version of the `runaway' effect, which would result in all galaxies moving in random directions at nearly the speed of light. Other more general issues regarding negative mass in general relativity are discussed, such as the possibility of time-travel paradoxes.