This question already has an answer here:
Firstly, I apologise if my thinking is completely incorrect - I am by no means a physicist (yet!), I have included layman illustrations to hopefully assist in explaining my thinking.
I am imagining the big bang to be, for lack of a better word, an explosion, thus the universe to be progressively expanding:
Therefore, to me it seems logical to suggest that there is an edge.
If this is the case, then is it reasonable to suggest that explosion + edge = 'bright edge'? Where light projects in all directions at the edge, not just outwards into the 'nothingness'.
So, this brings me to my question: why, when someone looks deeply enough 'at the edge' do they see an absence of light?
Again, apologies if I'm jumping to irrational conclusions & am way off.