If a neutron star is made solely of neutrons that show no repulsion to each other, protons and electrons have merged by overcoming electron degeneracy pressure so all the empty space taken up by electron shells is removed, how do u get anything denser to the level of being a black hole? If a neutron star is neutrons packed as closely together as can be, as they are fermions and obey the Pauli exclusion principle, to make a black hole do the neutrons merge to form some kind of boson? From research I'm getting the impression that it's something to do with the Heisenburg Uncertainty Principle. Uncertainty in space X Uncertainty in momentum = Planks constant / 4pi. As things are made more dense the uncertainty in space decreases as you can work out where they are easier so this increases uncertainty in momentum. If things have more momentum they create more outward force so stop collapse to higher density. But surely if the mass were great enough to overcome this force the uncertainty in space would be even less and so give particles an even greater momentum. So are black holes made up of bosons or am i not getting the point to the uncertainty principle or is there something else entirely?