Inhomogeneities as a bias and as a probe

Precision Cosmology requires us to take into account the small scale inhomogeneities in the Universe when discussing cosmology After a general introduction I will discuss the effect of small scale inhomogeneities on the luminosity distance redshift relation within LCDM: 1 How inhomogeneities bias the Hubble parameter due to peculiar velocities 2 How inhomogeneities serve as a probe of the primordial power spectrum on small scales through the lensing dispersion of Type Ia Supernovae