The cosmic microwave background (CMB), the oldest light in the universe, has brought us a wealth of precision information about the contents and history of our cosmos. It may also bear the signature of yet older messengers: a primordial hum of gravitational waves, seeded by inflation during the first moments of cosmic evolution. These ripples in spacetime should have left a unique signature on the CMB: a faint “twist” pattern in its polarization. I will discuss the hunt for this elusive signal, with a focus on SPIDER, an ambitious balloon-borne instrument deploying thousands of superconducting detectors to the skies over Antarctica. I will give an update on SPIDER’s 2015 flight and preparations for its second in 2018, as well as related efforts to tease out new fundamental physics from cosmological observations with cryogenic detectors.