Here’s a little quantum mechanics to entertain you.
It’s 4-ish am, so why not.
Atoms contain things called particles: protons, electrons, etc. In a very crude sense, these particles “spin.” They go round and round and upside down and all over the place. All this “spinning” gives the particles momentum…angular momentum since they are going round and round and such. The spin is given a number that is a measure of the momentum. These numbers are simply 1, 2, 3, etc. But only some of the particles have spins of 1, 2, 3, etc. These particles are bosons. Some particles have spins that are half the value of boson spins. These particles are fermions.
Atoms have energy levels that particles can live in. These energy levels are like spherical stepping stones. Each particle has a specific amount of energy, and the amount of energy it has determines which outer sphere, or shell, or orbit, it runs around in. A particle can jump from one orbit to another as it gains or loses energy. The energy levels have the same center, the nucleus, which is made up of more particles, and the farther away an orbit is from the nucleus, the greater its energy level is, which means that a particle needs lots of energy to run around in it. Particles like to be in the first orbit, the ground state, closest to the nucleus, because they don’t need so much energy to hang out there.
Still not terribly exciting, but…
When something excites the atom (gives it energy) the particles absorb this energy and jump to outer orbits. The particles then fall back down to lower orbits, and the energy they lose is released in the form of a photon, a little wave packet of light. Different atoms (atoms from different elements) have different energy levels and therefore give off different combinations of light. These combinations are called fingerprints, and each element has its own unique one. That’s how we know what elements are in stars. We look at the light from a star through a special tool called a spectroscope, which breaks up the light into its different wavelengths (an indication of energy). Red has a certain amount energy, blue another, etc. We use this property to make neon lights. The name neon refers to the neon gas inside the glass tubes. Neon atoms give off an orangy red color. Other gases are used to give off other colors to make pretty signs. We call those signs neon, too, because neon is the generic term that the general public associates with that type of lighting.
That is pretty cool, and the whole spin/photon stuff gets even better, but let’s redirect.
Bosons in an atom can have the same energies and run around on the same orbits, but fermions can’t. So when a star starts to lose its umph, as its nuclear forces degenerate, the internal pressure that keeps the star stable decreases, and all those bosons and lovely orbits housing all those lovely stubborn massive fermions start to collapse into the star, making a super dense, super pressurized clump of matter. The pressure could become too great for the star to handle, and depending on the star’s stage of life, the star could collapse in on itself and suck everything around it right on in. Even light. That’s some crazy hole. A black one.
Fermions are pretty badass.
Two guys, Paul Dirac and Enrico Fermi, figured out not so long ago that these fermions can’t enjoy each other’s company.
Which means that even though fermions are possibly the most awesome particles, they are the loneliest.
If you made it all the way to the end of this post without falling asleep, I’m impressed. Not many people find this stuff interesting. But given that fermions are considered to be the bulk of all matter, then you, Reader, now know more about yourself. Literally. And that really is interesting.