Monday, January 08, 2007

Exposing Dark Matter

Given the political nature of most of the rantings here, readers might be inclined to think this would be a post about the dark and fetid underbelly of the Bush administration. Happily, I can say that this is a post about a far more inherently interesting subject, one that can be verified through observation and reason, rather than FOIA requests (not that those do much good these days).

Since the early days of modern astronomy, rotation curves of galaxies revealed that there was more matter -- or something -- surrounding these galaxies than was being directly observed. These early observations have only been confirmed and amplified with every new generation of telescope. Recent instruments, including the Hubble Telescope and WMAP, vastly increased the estimate for how much dark matter and dark energy existed in the universe. Today, it is estimated that only 4% of the energy density of the universe is composed of baryonic matter. And while there are many notions of what dark matter might be, dark energy remains an utter mystery. Nonetheless, as our instrumentation has improved, our "understanding" of the universe -- or rather our understanding of our understanding of the universe -- has diminished by orders of magnitude. Much like the Bush administration, 96% of the universe is essentially mysterious.

Recently and using data from the Hubble Space Telescope's Cosmic Evolution Survey (COSMOS), astronomers presented their 3D map of a large piece of the sky at the current AAS meeting in Seattle. And it is a beaut (click for larger image):

There is dispute about dark matter/energy, of course, with some claiming that the supposed effects manifest by dark matter are really variations in gravity, that gravity is anything but constant in all parts of the universe. But then this hasn't been observed directly either.

But such is the nature of science. And no matter what creationists will tell you, there are always arguments.


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