Superfluids are strange states of matter, typically forming at very low and very high temperatures, exhibiting gonzo properties like a seemingly gravity-defying tendency to climb up the walls of containers and friction-free superconductivity. That is, they are perfect conductors that don't lose energy during transmission. And the fact that they appear to exist at the center of neutron stars tells scientists a lot about nuclear interactions in high-density matter and the life-cycles of neutron stars. The pressure within neutron stars is so intense that in the stars' cores, charged particles merge, resulting in a star mostly consisting of neutrons (hence...