# $R_h=ct$ and the eternal coasting cosmological model

## TL;DR

The paper discusses the $R_h=ct$ cosmological model as a special case of an eternal coasting universe, highlighting its historical antecedents and its ability to avoid common cosmological problems, including the coincidence problem.

## Contribution

It reveals that the $R_h=ct$ model is a flat case of a broader class of eternal coasting models with advantageous properties.

## Key findings

- $H_0 t_0=1$ in these models
- The models avoid the cosmological problems of standard models
- The ratio $rac{oxed{ ext{Omega}_m}}{oxed{ ext{Omega}_{dark ext{ energy}}}}$ is constant

## Abstract

We point out that the nonempty $R_h=ct$ cosmological model has some known antecedents in the literature. Some of those eternal coasting models are published even before the discovery of the accelerated expansion of the universe and were shown to have none of the commonly discussed cosmological problems and also that $H_0t_0=1$. The $R_h=ct$ model is only the special (flat) case of the eternal coasting model. An additional feature in the coasting model is that $\Omega_m/\Omega_{dark \; energy}$ = some constant of the order of unity, so that also the cosmic coincidence problem is avoided.