Nils Andersson is a professor of mathematics and an expert on Einstein's theory of relativity and related astrophysics. His research mainly concerns black holes, neutron stars and gravitational waves. Over the last couple of decades, he has actively pursued many issued relevant to the emerging area of gravitational-wave astronomy. His current work focusses on the extreme physics that neutron stars represent, from the state and composition of matter to the dynamicalrole of the superfluid and superconducting components expected to be present in the core of a mature neutron star. Less