Subject: Questions regarding space/time expansion?

Questions regarding space/time expansion?
Is it possible to physically or mathematically describe a quantity of 
mass per given volume that will halt and/or reverse the expansion of
space time locally over a given set of geometric limits and yet still
allow the rest of the universe to continue expanding virtually
unaffected? Am I describing a black hole, and if so, do black holes
experience a big crunch similar, yet different, to that which may 
await our universe? Is it a degree of mass or mass per unit volume?
Are there differences? Could the cosmic microwave background radiation
be Hawking's Radiation given off by the universe. Could that explain 
it's omnipresence? If so, where does the other particle of the virtual
pair radiate off to? Thank you.

Re:Questions regarding space/time expansion?