Marc Kamionkowski Johns Hopkins University theoretical physicist Marc Kamionkowski is one of three physicists to be awarded the 2021 Gruber Cosmology Prize for their contributions to methods essential for studying the early universe. The prize recognizes Kamionkowski’s discovery of a mathematical means to use radiation from the cosmic microwave background (CMB)-a relic of the earliest days of the universe-to glean information about what happened as far back as the first fraction of a second of the universe’s existence. The method involves measuring polarization, or the degree to which an oscillating wave, bouncing up and down relative to the direction of travel, diverges from a strictly perpendicular orientation.