I can't even find the quote about the Expanse being 50 light years from Earth - I think someone may have just added this, based on warp speeds (i.e. complete speculation), to Memory Alpha.
So, I propose the following:
- 1). - The Expanse is a relatively flat phenomenon 2000 square light years in area.
- 2). - The Expanse is very distant from Earth, perhaps over 100 light years.
Both proposals would make the idea easier to accept.
2000 square light years, means a diameter of only 45 light years - Soval used bad language.