Genius Brian Green was asked this question
He believes 2 things :
1) it was only the bang for our own part of the galaxy and many bangs occurred before
2 or it’d a pointless question like asking , “ what is North of the North Pole”
All math breaks down at the BB due to infinite numbers
Greene believes “ repulsive gravity “ was what caused the massive explosion to stretch 14 billion light years in seconds Due to bizarre quantum fluctuations