When neutron stars dance together, the grand smash finale they experience might create the densest known form of matter known in the Universe. It’s called “quark matter, ” a highly weird combo of liberated quarks and gluons. It’s unclear if the stuff existed in their cores before the end of their dance. However, in the wild aftermath a neutron-star merger, the strange conditions could free quarks and gluons from protons and neutrons. That lets them move around freely in the aftermath. So, researchers want to know how freely they move and what conditions might impede their motion (or flow).