So we can go and measure the numbers that go with those predictions. There are two different lines of evidence now, and I think that the evidence is very firm. The supernova results give evidence that the expansion of the Universe is increasing as a function of time. So there are two very different lines of evidence indicating that the Universe is accelerating. I believe it now.
Nobody has any idea, which is why it is so interesting.
And this is also another reason to compare this with a physics experiment, because this is not the conventional topic studied by astronomers. MAP is an intermediate step between Boomerang and Planck. It will achieve all-sky coverage, but will not have the sensitivity, nor the angular resolution, nor the frequency coverage of Planck. Many, of course. In terms of the CMB itself, we will still want to know more about the polarisation.