Reading a popular cosmology article (a hobby), I caught note of a hint that some models of physics suggest quintessence need not have a modal state. This is interesting because observations of distant stars and galaxies suggest that about a billion years ago the expansion of space accelerated. The lay assumption is that expansion will now continue at this accelerated pace, and that the universe will slowly dwindle into nothingness.
It is a bit odd, though, that such a great even should occur just as life on earth began to appear. Odd.
Not such an odd coincidence, however, if quintessence varies in an erratic way. We know space expanded very fast as the universe was "born" (the big booooooiiiiiiiiinnnnngggg), and then we think it expanded fairly smoothly, then it sped up. But maybe it speeds up and slows down all the time, sometimes with big jumps, sometimes small jumps. Maybe it's even uneven, like baking bread. Maybe some times and places it even contracts (and there, does time run backwards ... but of course if time ran backwards forwards and sideways for us we'd never know -- our awareness points from birth to death irregardless of how an observer might see us).
Maybe the universe belches and bubbles and breathes, a scaled up version of quantum foam.
It's nice being an unrestrained speculator.
Of course it did, then we might really have no idea how old the universe really is, nor is it clear what "old" would mean in that context. Age might be variable.
Fred Hoyle might be pleased.
9/27/2007: Alas, I've read a few good lay books on cosmology since I wrote this post, and it turns out this expansion is an unfortunately good fit for current theory. My non-physicist interpretation is that space has a invariant "springiness" that is constant for all time, but gravity's effect wanes with distance (inverse square of course). So gravity's getting weaker and weaker, the spring never weakens, and the expansion constantly accelerates. Only things firmly bound by gravity (milky way, some neighboring galaxies) will remain in Sol's future light cone.