On the Growth of the Number of Hyperbolic Gravitational Instantons with   respect to Volume
  In this paper, we show that the number of hyperbolic gravitational instantons grows superexponentially with respect to volume. As an application, we show that the Hartle-Hawking wave function for the universe is infinitely peaked at a certain closed hyperbolic 3-manifold. 
John G. Ratcliffe and Steven T. Tschantz