Krauss is very explicit about what he means by 'nothing'. He does NOT mean two energies existed balancing each other at all.
No energy, no time, no matter - NOTHING!
He uses 240 pages to redefine nothing, as a void seething with activity, virtual particles popping in and out of existence.
The Pre- Big bang workshop is full of potential. and we have not touched Roger Penrose yet.
The BB, and Evolution are latecomers to the saga of existence. The gods question even later.