The Quest for Primordial non-Gaussianity

Vanilla single-field, slow-roll inflationary theory predicts that primordial fluctuations in the universe were nearly Gaussian random, although some very well-motivated models specifically predict observably large non-Gaussianity. Measurements of primordial non-Gaussianity therefore represent a rare window into the physics moments after the Big Bang. I first review the history of measurements of non-Gaussianity from the cosmic microwave background (CMB) anisotropies over the past two decades.  I then review results obtained over the past five years showing the signatures of primordial non-Gaussianity in the large-scale structure (LSS). Finally I discuss the current and forecasted future constraints on classes of models for primordial non-Gaussianity from the combination of the CMB and LSS, and how they probe the physics of the early universe.