By PAUL DAVIES - GUARDIAN.CO.UK
Added: Thu, 24 Dec 2009 00:00:00 UTC

Thanks to LWS for the link.
http://www.guardian.co.uk/commentisfree/2009/dec/23/dark-matter-key-understanding-universe#start-of-comments

When Henri Becquerel spotted that photographic plates became fogged if kept in a drawer next to uranium salts, the discovery of radioactivity was immediate. By contrast, other scientific findings – global warming, for instance – take place incrementally, the result of gradually accumulating evidence. Last week, scientists announced a small but potentially significant step in our slowly evolving understanding of what the universe is made of.

Astronomers have long known the stars contain the same atoms as those found on Earth. But for years evidence has been growing that most stuff in the cosmos is not made of atoms or subatomic particles at all, but Something Else.

The first inkling that the universe is dominated by unseen material came from the observations of clusters of galaxies made in the 1930s. The astronomer Fritz Zwicky noticed that within the clusters, galaxies mill around so fast that the clusters ought to fly apart. So what keeps them intact? The simplest explanation is that some form of dark matter provides the necessary gravitationally binding.

Today, cosmologists can put a precise figure on the amount of dark matter in the universe: about five times the mass of the luminous, common-or-garden variety of matter. And its role in shaping the cosmos is crucial. After the big bang that created the universe 13.7bn years ago, matter was spread smoothly through space. Aided by the gravitating power of the dark component, ordinary matter was pulled into clumps, which later evolved into galaxies that spawned stars, planets and, in one case at least, life.
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http://www.guardian.co.uk/commentisfree/2009/dec/23/dark-matter-key-understanding-universe#start-of-comments

TAGGED: SCIENCE, SPACE