New insights into the properties of neutron stars have come from two independent analyses of gravitational waves from the GW170817 neutron-star merger. The work was done by teams led by Farrukh Fattoyev at Indiana University Bloomington and Eemeli Annala at the University of Helsinki. The teams used different methods to calculate the relationship between the radius and mass of neutron stars and came up with the same result. In October 2017 the LIGO and Virgo detectors made the first-ever observation of gravitational waves from two neutron stars as they spiralled into each other and then merged to form a black...