A New Window to the Early Universe

Small temperature variations in the cosmic microwave background (CMB), the radiation left over from the big bang, have shed much light on the early universe. According to predictions, the CMB should also be polarized, providing a better test for early-universe theories than temperature alone. In their Perspective, Hivon and Kamionkowski highlight the recent detection of the CMB polarization. The new results end a 34-year quest to verify the predictions, but are only the first of many upcoming studies of the CMB polarization.