Gravity Driven Inflation

The union of high-energy particle theories and gravitation often gives rise to an evolving strength of gravity. The standard picture of the earliest universe would certainly deserve revision if the Planck mass, which de nes the strength of gravity, varied. A notable consequence is a gravity-driven, kinetic in ation. Unlike standard in ation, there is no potential nor cosmological constant. The unique elasticity in the kinetic energy of the Planck mass provides a negative pressure able to drive in ation. As the kinetic energy grows, the spacetime expands more quickly. The phenomenon of kinetic in ation has been uncovered in both string theory and Kaluza-Klein theories. The di culty in exiting in ation in these cases is reviewed. General forms of the Planck eld coupling are shown to avoid the severity of the graceful exit problem found in string and Kaluza-Klein theories. The completion of the model is foreshadowed with a suggestion for a heating mechanism to generate the hot soup of the big bang. To appear in the conference proceedings, \Uni ed Symmetry: In the Small and the Large II" (Eds: B.N. Kursunoglu, S. Mintz, and A. Perlmutter).