grand unification transition

At this point the universe had cooled enough for gravity to be defined by Einstein's general relativity theory, but the temperature was still sufficiently high that the other three forces remained united. The Grand Unification theory holds that the three forces which are often perceived to be independent, the strong, weak and electromagnetic, are actually components of a single unified force. All are related by an underlying symmetry, so all components are described by a single force law. It is when the symmetry of these forces is broken that a phase transition takes place. In the present universe the symmetry is completely broken and therefore the forces are defined individually. The critical temperature for the phase transition to the next state of the universe was about 10²⁷K.

The spontaneous symmetry breaking is due to a set of fields called the Higgs Fields. Their function is to break internal symmetry without destroying underlying symmetry. Each is specified by giving its value, a single number for each point in space. Grand unified symmetry is maintained when all the Higgs fields have a value of zero and is broken if one or more of the Higgs field have a non-zero vale. It is the Higgs field mechanism that leads to the changes in state of the universe.

- Jx