Speaker: Dr. Shatanu Desai, Ludwig Maximilian University, Munich.

The Nobel Prize in Physics for 2011 was awarded for the discovery that the expansion of the Universe is accelerating. Yet the physical origin of cosmic acceleration (also known as "dark energy") remains a mystery. In this talk I shall discuss two ongoing and one future experiment designed to address the dark energy conundrum. One of them is the South Pole Telescope which is a 3-band mm-wave telescope located at the South Pole and completed a 2,500 square degree galaxy cluster survey in 2011.  The next is the Dark Energy Survey, which is an ongoing  5,000 square degree photometric survey of the southern skies and  will probe the dark energy equation of state through four complementary techniques: galaxy clusters, large-scale galaxy clustering, weak gravitational lensing, and supernovae. Finally, I shall discuss the Euclid  space-based mission to study dark energy, which will be launched around 2020.