Read this cool article on the Discover Magazine astronomy blog about galaxy NGC 3021, the idea of a "cosmic bootstrap device" and how it is used to guess the accurate distance of objects from, the speed at which they move away from us, and ultimately the speed at which the universe is expanding. It's fairly amazing.
Among other things, this articles offers this compelling reason why knowing the speed of expansion could clue us into other things:
Writes Phil Plait, "By knowing this number accurately, all we have to do is measure how fast the galaxy is moving away from us — a very easy measurement to make — and we can find its distance. Of course, it’s more complicated than that, but that’s the basic idea.
"But by nailing down all these numbers, we can in turn nail down such things as how much dark energy is in the Universe, and maybe even rule out some theories as to what this mysterious stuff is. It’s pushing on the fabric of space and time, making the Universe swell faster every second of every day, and we have no clue what it really is. Well, that’s unfair: we have lots of clues, but we don’t know what’s causing it. Observations of NGC 3021 and other galaxies like it will help us unravel some of these mysteries, which are among the biggest in science today."
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