In the aftermath of the creation of a neutron star, it can have a variety of masses, many of which are far in excess of the most massive white dwarf. But there is a limit to how massive they can get before becoming a black hole, and a simple nuclear physics experiment on a single proton may have just discovered why. (NASA)

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.