A Thought.... It seems to me ((Though I may be wrong about this)) that most people think that though the universe isn't slowing it should be, due to the effects of gravity. I don't know if this has been said before, but gravity would also make the universe expand faster, meaning that the universe should (If there is no other force effecting the expansion except for gravity) be expanding at a constant rate. If any one point were to be pulled one way by gravity, since the universe seems more or less the same through out, it would be pulled the other way as well. These two forces would cancel, and as such the universe would keep on expanding at a constant rate (More or less).