2024-11-27 02:06
Great question! In short, it's unknown and might be unknowable.
Broadly, many think that there isn't anything there. A true absence which is hard for us to comprehend. The big bang wasn't like a bomb exploding in a room but an explosion that created the room through its expansion.
Other theories are that we are expanding into the space between universes, or perhaps even pressing against them.
🙂