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limiting curvature and nonsingular gravity Damien Easson McGill We will consider the theory obtained by adding to the usual dilaton gravity action specially constructed higher derivative terms motivated by the Limited Curvature Hypothesis (LCH) and determine the spatially homogeneous and isotropic solutions to the resulting equations of motion. All solutions of the resulting theory of gravity with these symmetries are nonsingular and all curvature invariants are bounded. For initial conditions inspired by the pre-big-bang scenario solutions exist which correspond to a spatially flat Universe starting in a dilaton-dominated superinflationary phase and making a smooth transition to an expanding Friedmann Universe. Hence, the graceful exit problem of pre-big-bang cosmology is solved in a natural way. We then consider the use of the LCH in the (ongoing) construction of a nonsingular four-dimensional Schwarzschild black hole. We point out that scenarios in which the universe is born from the interior of such a black hole may not posses many of the problems of the Standard Big-Bang (SBB) model. In particular we demonstrate that the horizon problem, flatness, and the structure formation problem might be solved naturally, not necessarily requiring a long period of cosmological inflation. The black hole information loss problem is also discussed.
Wednesday, December 5th 2001, 12:30 |