Testable Consequences of Curved-Spacetime Renormalization
  I consider certain renormalization effects in curved spacetime quantum field theory. In the very early universe these effects resemble those of a cosmological constant, while in the present universe they give rise to a significant finite renormalization of the gravitational constant. The relevant renormalization term and its relation to elementary particle masses was first found by Parker and Toms in 1985, as a consequence of the ``new partially summed form'' of the propagator in curved spacetime. The significance of the term is based on the contribution of massive particles to the vacuum. In the present universe, this renormalization term appears to account for a large part or even all of the Newtonian gravitational constant. This conjecture is testable because it relates the value of Newton's constant to the elementary particle masses. 
Leonard Parker