The Universe today displays a hierarchy of structures: stars are gathered into galaxies, which are mostly grouped into clusters of varying sizes. These in turn are arranged along cosmic filaments, surrounding large voids. This rich structure is believed to have developed from the small fluctuations in density which we see imprinted on the cosmic microwave background under the driving force of gravity, acting primarily on the dark matter which dominates the mass budget of the Universe. In this course we will study the way in which these structures develop, and the nature of the characteristic objects which emerge. Galaxies and clusters display many scaling relations which give clues to the processes which formed them. Finally, we will look at the way the observed properties and distribution of these structures can be used to draw conclusions about the fundamental properties of the Universe as a whole, and about its evolution. |