The quantum cosmology of a higher-derivative gravity theory arising from the heterotic string effective action is reviewed. A new type of Wheeler-DeWitt equation is obtained when the dilaton is coupled to the quadratic curvature terms. Techniques for solving the Wheeler-DeWitt equation with appropriate boundary conditions shall be described, and implications for semiclassical theories of inflat...

Near the horizon of a black brane solution in Anti-de Sitter space, the long-wavelength fluctuations of the metric exhibit hydrodynamic behaviour. For Einstein’s theory, the ratio of the shear viscosity of near-horizon metric fluctuations η to the entropy per unit of transverse volume s is η/s = 1/4π. We propose that, in generalized theories of gravity, this ratio is given by the ratio of two e...