Black Holes, White Dwarfs and Neutron Stars

Compactness

Compact is something of a euphemism when we refer to neutron stars and black holes: the typical example has the mass of the sun contained with a radius of only 10km. Perhaps a more easily accessible comparison is that a sugar-cube of neutron star material could contain as much mass as all the human beings on earth added together. (An overestimate of 10 billion people at 100kg each gives 10¹²kg, wheras 1cm³ of neutron star matter at a density of 10¹⁵g cm^-3 would also contain 10¹²kg.)