particle soup

The mix of different types of particles changed constantly during the early moments. Photons crashed into one another, producing particle-antiparticle pairs. These pairs then annihilated each other in a flash of light. So the particles and radiation were always interacting, resulting in a soup-like texture, a condition of thermal equilibrium.

The type of particles that could be produced in this way was dependent on the temperature of the radiation. According to Einstein's equation E=mc², any particle can be produced if the available energy is at least the mass of the particle times the speed of light squared. As the temperature cools there is less and less energy available, so it follows that as time goes on less and less massive particles will be created.

- Fx