Murat Özinan

If you drop an ice cube into a glass of water, it will float until it melts. But if you cool the water slowly, at some point it all freezes at once: that's a first-order phase transition: abrupt, with a clear boundary.

In a binary star system, one star pulls matter from its companion. Over centuries, this material settles onto the surface of a neutron star — the ultra-dense remnant of a dead star. This process, called accretion, usually proceeds smoothly. Gravity behaves as general relativity predicts, without surprises.