The focus of his research is cosmology, where he attempts to understand the contents and evolution of the Universe. A large part of his research involves the observation of the cosmic microwave background (CMB), the faint afterglow left over from the Big Bang, and exploring the nature of dark matter through measurements of gravitational lensing from clusters of galaxies. He has worked on several previous experimental efforts to study the properties of the CMB, including the Wilkinson Microwave Anisotropy Probe (WMAP), the Boomerang long duration balloon experiment, the BICEP experiment at the South Pole, and the NASA/European Space Agency's Planck satellite.