Low-energy dynamics of gravitation

The present status of theories of quantum gravity are reviewed from the low energy point of view. String theory relates classical black-hole type solutions of Einstein-like equations (e.g. axidilaton gravity) to the string vacuum. Several such solutions are proposed and their properties are investigated, including their behavior under supersymmetry transformations. A general feature of all possible quantum theories of gravitation is that they lead to a field theory description at low (as compared to the Planck mass) energies. The theoretical consistency, uniqueness and consequences of such an effective theory are investigated. I show that a power counting theorem allows for the momentum expansion that defines the effective theory even in the presence of large masses. I also show that graviton-graviton scattering is free of potential infrared and collinear divergencies that plague perturbative discussions of Yang-Mills theories