Modern cosmology is founded on an understanding of how gravity affects the distribution of matter in the universe. The currently accepted paradigm is that gravitational instabilities amplify small ripples imprinted in matter and radiation in the early universe, and these fluctuations eventually evolve into the observed web of cosmic structures. I will review this paradigm and describe recent developments in our understanding of the nonlinear clustering properties of galaxies and dark matter. I will also discuss the implications for upcoming cosmic microwave background measurements.

ANL Physics Division Colloquium Schedule