"Suppose in the dawn of time there was a mixture - a soup or a blob - of protons and electrons floating in space [Concept 1]. Most of space is empty, because these particles are very small. The only force felt by the particles is the electromagnetic force, because it is long-range. The strong force is like glue on the surface of the protons [Concept 2]. If a proton hits another proton, it will immediately stick to it. But protons repel each other due to their like charges, so they never do. Instead, protons attract electrons, which quickly begin orbiting around them like planets, forming hydrogen, an atom with one proton and one electron. This is the basic material of the universe, and the primary element in stars."