Name: Teppo Mattsson
 Institution: University of Canterbury
 Title: On the role of shear in cosmological averaging
 Key Words: inhomogeneous cosmology, cosmological averaging, dark energy, structure formation
 Abstract: Due to the nonlinear backreaction of cosmological inhomogeneities, the average expansion of the universe may not evolve like in a homogeneous Friedmann model. Using an exact solution of the Einstein equation for a void-wall configuration, we demonstrate how the shear can suppress the backreaction by a factor of 10^(-5) relative to the value obtained by neglecting the shear. The suppression may not hold in the real universe, if it is dominated by uncompensated voids.