By the Book 11

Ok maybe this won’t take as long as I thought it would. What is a hadron? A hadron is a particle made of quarks. There are 2 different kinds of hadrons, the mesons and the baryons. Mesons are made of a quark and an anti-quark, (wait…I talked about this before didn’t I?) and baryons are made of 3 quarks. There are also anti-baryons, made up of 3 anti-quarks. I’ve attacked a table of a large number of the hadrons (and the quarks). There are two of importance to our everyday lives, the proton and the neutron. They are each baryons made of 3 quarks and…obviously they are our everyday nucleons at the center of all of our atoms.

Ok, so back to the hadron era. Just like the lepton and radiation eras the reason it’s called the hardron era is because it is dominated by hadrons. Hadrons are very heavy particles, at least compared to electrons or massless photons. So they take more energy to make (remember E=mc^2. You see it is useful for more than just the atomic bomb), and consequently the early universe can only produce them at very high temperatures. And as we go back and back temperatures get higher and higher and consequently we have a hadron era, but there are some subtleties…that I will talk about another day.