The whole universe was contained in the Big Bang. It's not like the debris of an explosion expanding through space, rushing away from some central point. The whole space was once confined to a small point. The whole space is expanding. The Big Bang is everywhere, which is why the Cosmic Microwave Background comes from all over the sky.
And who made the thing that went, "Bang," hmmmm? If there ever were such a theoretical thing which I highly doubt.
I am no scientist, I am an artist, nevertheless I enjoy thinking on these things and hearing others thoughts and observations. In my way of thinking, if all dimensional space is contained at some "point" along with all the matter of the universe just before the big bang (and is expanding as matter expands) then where was that "point" contained? i.e., what was the field or backdrop for that "point"? Was it nothing? If so, I cannot wrap my mind around nothing where something existed.
I have heard that there are perhaps as many as ten dimensions which make up our universe, of which only three are perceived by our senses, and a forth may be inferred or mathematically shown. This is intriguing but has no other meaning for me other than, that the other dimensions make up what I believe is the spiritual realm.
I do read the Bible, and I believe in God and that He is the mind behind the great expanse of our universe. And not until death will we see the multidimensional reality of our existence. I also believe that the mind that is not prepared to see the face of God, will be forever after separated from His presence. A place where perhaps God called something out of nothing, a place of outer darkness as described by Jesus in the book of Matthew chapter 22 verse 13.
You know this is incomprehensible, don't you?
Assuming this small point was in the middle of nowhere and now it isn't in the middle of anywhere and the expansion is ongoing at an indeterminate rate, any manner of suppositions could and will be made regarding its origin, makeup and future.
The human mind isn't large enough for such a notion.