Neutron stars are composed of the densest material known in the universe, surpassing even the density of an atomic nucleus. A sugar-cube-sized amount of this material would weigh billions of tons on Earth. The immense gravity compresses protons and electrons into neutrons, forming a neutron-rich substance with extraordinary properties. This extreme material, often referred to as neutronium or nuclear pasta, exists under pressures far exceeding anything achievable on Earth and exhibits unique behaviors like superfluidity.
