Taking the Measure of Dark Energy

Cosmological distance measurements are challenging but fundamental to our understanding of the expansion history of the Universe. With the more precise techniques developed in the last decade, we have determined that the expansion rate is accelerating. This strange and unexpected result is attributed to a new force dubbed �Dark Energy,� for lack of any deeper understanding. I will discuss a new method for measuring cosmic distances, Baryon Acoustic Oscillations, and an experiment that will bring this technique to a new level of precision in the ongoing effort to understand Dark Energy.