"pure" means more like "homogenized" when referencing the type. It's not like an element is a homogenous. "pure" energy can be a mixture of potentials. As they cool down these "potentials" begin to get closer together. Or maybe a better way to put it is they begin to interact. Then some repel and other pull together. Then the hadrons, and other particles "freeze" out. Like ice in water. But that's only less than 10% of what is known, so I don't know.-"photon" I don't think "are in there". they are produced when state changes.