According to science, at least in theory, black holes formation is quite straightforward. When a star dies and explodes, it will collapse into itself compacting a large mass into a small volume, and this is the basis of a black hole creation due to the acceleration of the gravitation within this system to speeds above the speed of light. But neutron stars never form black holes, despite the fact they are similar to the system presented above.
Neutron stars can avoid collapsing into themselves because they hold on to strong gravitation forces even though they commonly possess a mass twice as big as the Sun’s mass.
Now, the scientists know how neutron stars can resist to gravitational collapsing that would turn them into black holes by studying the particles which form neutron stars.
The scientists explain why neutron stars never form black holes
As science has found so far, there are two big classes of particles, namely, bosons and fermions.
All the known objects in the Universe are made of electrons, neutrons, and protons. Every proton and neutron is composed of three quarks, while electrons are elementary particles.
All these three particles are fermions and possess specific characteristics that made them incompatible with black holes formation. More specifically, electrons, neutrons, and protons are functioning obeying the Pauli Exclusion Principle, while bosons are not.
According to this principle, in a quantum system, two identical fermions will never possess the same quantum state. More precisely, if you put one proton into a quantum system, it will adopt a specific set of characteristics, but when you place the second proton, this one has to take a different set of attributes.
Neutron stars, made up mostly of neutrons, will never collapse further forming a black hole just because neutrons are fermions and they obey the Pauli Exclusion Principle which stipulates that these particles are incompatible with black holes formation.