Big Bang Time Line
Cosmological models of the "Big Bang" expansion of the universe have converged on a general framework in time, energy, and temperature. Below is an attempt to show some of the features of the models on a time line.
The later parts of this time line follow the chronology suggested by Steven Weinberg in "The First Three Minutes". The models are extended to earlier times back to the Planck time when the unification of all the fundamental forces is presumed. In order to deal with some problems with the standard big bang model, Guth introduced the idea of an extraordinarily rapid inflationary epoch. Along the time line there are three spontaneous symmetry breaks which separate the unified force into the four fundamental forces operating in today's universe.