Primordial black holes, phase transitions, and the fate of the universe
  Phase transitions in the early universe are prime settings for the production of primordial black holes, since they can break the relatively quiescent homogeneity and isotropy of Friedmann-Robertson-Walker (FRW) cosmologies. These epochs of "symmetry breaking," moreover, can affect the subsequent development of spacetime by changing the evolution of some FRW parameters, including the present age and density of the universe. We discuss the relative importance of such effects on constraining mechanisms of black hole formation. 
Mitesh Patel, George M. Fuller (UCSD)