Big Bang Two

The Big Bang Two refers to the explosion caused by the Doctor "rebooting" the universe after its destruction.

History
In 2010, all stars in the universe had gone supernova due to the unique circumstances of the TARDIS's destruction. The entire universe was destroyed except for the Earth and its moon. The TARDIS's continuing explosion, which, like the resultant destruction of the universe, was happening "at every point in history", acted as a replacement for the sun, keeping humanity alive.

When the Pandorica opened in 2010, it contained billions of atoms from the universe as it should have been. Some of these were the final traces of whole races that had been un-made by the cracks in the universe. As "the perfect prison", the Pandorica was also designed to emit a Restoration field which would preserve or restore whatever was inside it. This combination of pre-collapse atoms and the restoration field, had a restorative effect on a fossilised Dalek. This seemed impossible, because the Daleks had never existed, having been wiped from history, so there should have been nothing to resurrect. Upon working this out, the Doctor reasoned that if the restoration field could be transmitted to the entire universe, it would be recreated.

The Doctor used a vortex manipulator to fly the Pandorica directly into the heart of the TARDIS's eternal explosion. Since the TARDIS was exploding at all points in history, the particles and restoration field were present at every point in time. A new universe was created based on the old one, but with the Doctor having never existed. "Rebooting" the universe caused this new universe to proceed undamaged, because the TARDIS had not exploded. Thanks to the ability the crack in her room gave her to recall things erased by remembering them, Amy Pond was able to bring back, at least, her parents and Rory, and later the Doctor after she remembered who he was and focused on calling him back.

Behind the scenes

 * Because this new universe's survival hinged on certain omissions when compared to the history of the prior universe, it is unclear whether any previous Doctor Who adventures ever took place. However, it is assumed they did once Amy brought the Doctor back, as the content of River Song's diary were replaced.