Kind of deep on the nuclear physics angle, but interesting.
https://medium.com/starts-with-a-bang/t ... 808cb3817f
The Surprising Reason Why Neutron Stars Don’t All Collapse To Form Black Holes
There’s something very special inside a proton and neutron that holds the key.
There are few things in the Universe that are as easy to form, in theory, as black holes are. Bring enough mass into a compact volume and it gets more and more difficult to gravitationally escape from it. If you were to gather enough matter in a single spot and let gravitation do its thing, you’d eventually pass a critical threshold, where the speed you’d need to gravitationally escape would exceed the speed of light. Reach that point, and you’ll create a black hole.
But real, normal matter will very much resist getting there. Hydrogen, the most common element in the Universe, will fuse in a chain reaction at high temperatures and densities to create a star, rather than a black hole. Burned out stellar cores, like white dwarfs and neutron stars, can also resist gravitational collapse and stave off becoming a black hole. But while white dwarfs can reach only 1.4 times the mass of the Sun, neutron stars can get twice as massive. At long last, we finally understand why.
In our Universe, the matter-based objects we know of are all made of just a few simple ingredients: protons, neutrons, and electrons. Each proton and neutron is made up of three quarks, with a proton containing two up and one down quark, and a neutron containing one up and two downs. On the other hand, electrons themselves are fundamental particles. Although particles come in two classes — fermions and bosons — both quarks and electrons are fermions.
Why should you care? It turns out that these classification properties are vitally important when it comes to the question of black hole formation. Fermions have a few properties that bosons don’t, including:
they have half-integer (e.g., ±1/2, ±3/2, ±5/2, etc.) spins as opposed to integer (0, ±1, ±2, etc.) spins,
they have antiparticle counterparts; there are no anti-bosons,
and they obey the Pauli Exclusion Principle, whereas bosons don’t.
That last property is the key to staving off collapse into a black hole.