How We Got Into The Dark Matter Fix And How We Can Get Out
  The recent discovery of cosmic repulsion represents a major challenge to standard gravity, adding an apparent missing energy problem to its still not yet adequately resolved missing mass one, while simultaneously requiring the current universe to be a very special, fine-tuned one. We suggest that the resolution of these difficulties lies not in the existence of more and more exotic gravitational sources, but rather in the lack of reliability of the extrapolation of standard gravity from its solar system origins to the altogether larger distance scales associated with cosmology. We suggest a very different such extrapolation, namely that associated with conformal gravity, to find that all of these issues are then readily and naturally resolved. 
Philip D. Mannheim (University of Connecticut)