The big bang is the cosmic event that is theorized to have marked the origin of the universe. At that instant all matter and energy in the entire physical universe, and the four dimensions of time and space, were created from a state of enormous density, temperature, and pressure. Big bang theory is the widely held set of scientific explanations relating to the primordial big bang. Cosmology is the study of the creation, evolution, present structure, and ultimate fate of the universe; the big bang theory is, at present, the central, unifying model that guides cosmology.

Three subdivisions of cosmology (quantum, particle, and standard cosmology) deal with the big bang according to the length of time after the big bang event.

Quantum cosmology ranges from about 10-43 seconds to about 10-11 seconds after the big bang. Because no agreed-upon physical theory exists among scholars for this...