The Square Kilometre Array will be an enormous radio astronomy facility with first-light of the completed array expected by 2024, and initial operations beginning in 2020. The SKA will be a massive array of many receiving elements, and it will thus have both exquisite sensitivity and angular resolution, as well as an ultra wide field of view. The fully sampled field-of-view, of the order of 200 square degrees, makes the SKA effectively a 10-gigapixel ultra wide field spectroscopic radio camera. Survey science will especially benefit from this instrument. For example, a billion galaxy redshift survey out to z=2 can be completed within a year, and will be used to detect Baryonic Acoustic Oscillations in the galaxy distribution, leading directly to a measure of the Dark Energy equation of state parameter.

This is a slightly modified version of the abstract for a seminar I presented in 2008 at the University of Edinburgh