In a recent paper in Science Advances, Pablo B, Thales S, and Luis OS show that radiatively cooled relativistic plasmas can spontaneously emit coherent, polarized radiation via the maser instability. This is a universal feature of relativistically hot plasmas embedded in ultra strong magnetic fields, such as plasmas in the magnetospheres of neutron stars, and should also be observable in laboratory conditions. The paper was also featured in a long story in the national newspaper Publico (.pt) and at the IST website .(.en)