Elementary Particles and Their Interactions

Matter consists of a mêlée of elementary particles. There are protons and neutrons, made up of quarks, and many other short-lived massive particles. All atoms consist of protons, neutrons and an accompanying cloud of electrons - then there are electrons, muons and neutrinos, as well as the massless particles - photons. The very early universe is a unique laboratory for studying the rarest of particles. We see the faded brilliance of the fiery past, and can assemble clues that enable us to tr...