Commonly accepted theory of the beginning of what we know as the universe. Mostly hypothetical in the past, but now has confirmed measurements by a NASA satelite WMAP. Event horizon indicators place a space-time beginning focal point at 13.7 billion years reverse time. It is not understood what the state of pre-energy/matter was or the catalyst to the event, as the pre-state had no observable horizon.
The big-bang was either an anomaly or it was not.