Based on what I've gleamed from a couple NOVA type TV programs, it would appear based on our observations that all galaxies are moving away from us and each other at an accelerating rate. From what I can tell we infer the relative speed of galaxies based on observed light frequency shift which is more pronounced for galaxies more distant, and we infer distance based on the diminished assumed candle power of expected star types. So far so good, makes sense. But the general consensus conclusion that is being widely reported has me puzzled. The great 'mystery' of why the galaxies aren't slowing down due to their gravity on each other, and the conclusion that space itself must be expanding due to some unseen 'dark energy' seems like a more complicated explanation than is necessary. If our observable universe is surrounded by a large amount of mass either uniformly in a beautiful perfect surface of sphere (along with all the cool mathematics artifacts that so many people love) or more simply just other mass in clumps around us the effect would be the same. The accuracy of observations and sample size we have to date couldn't tell the difference. The galaxies closer to this other mass would be accelerating towards it faster than those farther away. Below are simple 2D representations of the 'expanding' universe as we see it. Wouldn't both case 1 and case 2 contain the same picture from our point of view for both time A and B ? What observations have been made that rule out case 2 or make case 1 more likely than case 2 ? Thanks.