Neutron stars are the remnants of massive stars that have exhausted their nuclear fuel and undergone gravitational collapse, resulting in an extremely dense object with a mass comparable to that of the Sun compressed into a sphere only tens of kilometers in diameter.

The podcast episodes discuss neutron stars as an alternative outcome of stellar collapse, providing context for understanding the formation and properties of black holes.Episode 44797 explores how neutron stars differ from black holes, while Episode 4495 mentions evidence suggesting neutron star cores may contain a unique state of matter called quark matter.