Somehow I finished high school and college without knowing much more than protons, neutrons, and electrons--which is where things were in 1932. Photons, quarks, neutrinos, even the W and Z have popped up in the news from time to time. But it's only recently that I realized there was a whole standard model with its own chart:
A proton, it turns out, is made of two up quarks and a down quark. A neutron is one up quark and two down quarks.
