Well, they got a shock. What the real meaning of that shock is, we may never know in our lifetimes. But it seems that not only is the expansion NOT slowing down enough to cause things to fall back together, the best it can be measured the expansion is not slowing from gravity at all. It is in fact speeding up. The pieces of the universe are accelerating outward.
Force equals mass times acceleration.
There must be an outward force. This of course assumes that we can trust observations made over a very long distance. We are assuming that the same principles apply to measuring light that has traveled the short distance from the sun to the earth and to light that has come across the universe over long periods of time. That may be the whole basis of the anomaly. But for now we do not know.