Scientists see evidence of first-order phase change in nuclear matter

New evidence suggests that protons and neutrons go through a "first-order" phase transition--a kind of stop-and-go change in temperature--when they "melt." This is similar to how ice melts: Energy first increases the temperature, and then, during the transition, the temperature stays steady while the energy transforms a solid to a liquid. Only when all the molecules are liquid can the temperature increase again. With protons and neutrons, the melted state is a soup of quarks and gluons. Scientis...