This belongs in Astronomy Q&A.
As of now this is one of the unanswered questions...space it's self seems to have no qualities at all as far as we know to cause everything to move away from everything else. There actually is no "fabric", we just use that as a coordinate system of measurement for rationalization, space is essentially nothing, but we try to turn it into something all the time.
Keep in mind that gravity, space, and time are all constructs of the human mind used to help us quantify the behavior we see, and nothing else. It is subject to change as we don't fully understand the universe, how can we fully understand out rationalization of it?
We have much to learn.
