Earlier this year, the team behind the Background Imaging of Cosmic Extragalactic Polarization instrument, or BICEP2 (photo below by “Amble”), reported the discovery of primordial gravitational waves – supporting the theory of cosmic inflation. It now seems that their observations could instead be explained by cosmic dust polarisation. In a recent Nature column, Princeton physicist Paul Steinhardt outlines some ideas for analysing the results of future experiments of this kind. He also makes the rather disturbing suggestion that inflationary theory may be unfalsifiable. If that is true, is it really science at all?