Fredagskollokvium: Watching Galaxies Fall: testing theories of gravity using large galaxy redshift surveys

The acceleration of the expansion of the Universe, driven by the mysterious Dark Energy, indicates that our theory of gravity may need revision. While Einstein’s theory passes precision tests on Solar System scales, it seems to break down or require some extra component on the very largest scales. It is possible to test gravity in the Universe in the same manner as on Earth and in the Solar System, by watching test particles (galaxies, and photons) fall towards more massive objects. The theory of structure formation describes how tiny perturbations in the density of matter grow under gravitational collapse to form the structures that we see today. In this talk I will demonstrate, with reference to the WiggleZ Dark Energy Survey and other future galaxy surveys such as 2dFLens, how the motions of galaxies and formation of structure can be used as a test of gravity on the largest scales.