Why is Random Close Packing Reproducible?

We link the thermodynamics of colloidal suspensions to the statistics of regular and random packings. Random close packing has defied a rigorous definition yet, in three dimensions, there is near universal agreement on the volume fraction at which it occurs. We conjecture that the common value of phi_rcp, approximately 0.64, arises from a divergence in the rate at which accessible states disappear. We relate this rate to the equation of state for a hard sphere fluid on a metastable, non-crystalline branch.