A neutron star is the ultra-dense remnant of a dead star. Deep inside, matter is like boiling soup: a liquid of protons that has become superconducting (flows without friction), and the vortices within it are like swirling bits of vegetables. Each vortex carries a magnetic field. Previously, it was thought that only electrons, scurrying through the surrounding plasma like ants between the 'vegetables', could move them. But, building on the ideas of Lev Landau and John Bardeen, researchers have discovered that neutrons, passing through the liquid like tiny bubbles, also create a force. This force emerges from the subtle effects of quantum theory and quantum thermodynamics — the laws of the microworld.

This discovery changes calculations of neutron stars' magnetic fields and explains glitches in the rotation of pulsars (cosmic lighthouses). Some stars become magnetars with fields billions of times stronger than Earth's. In an unexpected twist, the interaction is so weak that it's comparable to the pressure of light on a sail, yet it governs the life of the star — part of stellar evolution. To verify, scientists will resort to computer simulations.