Curvature and Cosmic Repulsion
  Some recent supernovae studies have extended the distance versus velocity Hubble plot to very high redshift, and have revealed the apparent presence of a cosmic repulsion. We show that such a repulsion has a natural origin within conformal gravity, a fully covariant candidate alternative to standard gravity, and that it arises from the gravitational field itself via the negative spatial curvature which conformal cosmology is required to possess. In this same cosmology the flatness, horizon and cosmological constant problems are all resolved, and no need is found for dark matter. 
Philip D. Mannheim (University of Connecticut)