The cosmological constant was a fudge factor introduced by Einstein in an attempt to create a static Universe. Does this prove that the Universe is static?
No - as I understand it, it means accelleration, with more rapid acccelleration over time, as objects get further apart. Truely anti gravity.
Hmmm.... the "Cosmological 'Constant'" is not so 'constant' after all. 'Fudging' with equations to satisfy the data on the false premise of a static universe yields an expanding universe in observational fact, as we now understand. If the universe were to be slightly less homogenous than presently perceived, could the "Big Bang" itself be a more local universe phenomenon in a greater whole?
Oh, I see. The article wasn't very clear. Here's how it works.
Einstein's equations without the cosmological constant provide for essentially three solutions: a universe that collapses back upon itself, or a universe that expands forever, slowing down somewhat as it goes, or a universe that expands forever, but whose expansion eventually slows to a crawl. You can think of these as being akin to ballistic trajectories: the parabolic arc of an artillery shell, the escape trajectory of a deep space probe, or the orbital launch of a space shuttle.
Einstein assumed that the universe would neither expand nor contract, so he added in the cosmological constant. This parameter, depending on its value, can fine-tune the fate of the universe: the universe can collapse like the spiking of a volleyball, or it can accelerate outwards ever faster, like a rocket, or it can just hover in place, which is what Einstein wanted it to do.
Some time later, Edwin Hubble discovered that the universe was indeed expanding. It wasn't what Einstein expected, but it did seem to fit with the expanding cosmologies predicted if the constant were zero. So everyone assumed the constant was simply zero.
In recent years, however, it was discovered that the universal expansion isn't slowing down as required. In fact, it's speeding up! This most recent measurement confirms it by using Type 1a supernovae, which all have the same brightness. This allows us to measure how far away they are by how dim they appear. Also, we can measure how fast they are moving away from us by their redshift, and by how slowly they appear to cool off. That gives us all we need to see how the expansion has changed over time, if we can find enough Type 1a supernovae at a wide variety of distances.
If the expansion of the universe is speeding up, that means it can't be following one of the "ballistic" trajectories described by a zero cosmological constant. The constant must have a nonzero value very different from what Einstein originally wanted--opposite sign, in fact--but it must be nonzero nevertheless.