Saturday, August 25, 2007


And you thought Kansas was empty.
Astronomers say they’ve apparently found a giant hole in the universe - a practically empty zone, called a void, whose gaping size is hard to explain.

While past studies had revealed other voids, this one dwarfs them all, researchers say, being nearly a billion light-years across. [Something over six million billion billion miles.] ....

“We never even expected to find [a void] this size,” said Lawrence Rudnick, an astronomer at the University of Minnesota in Minneapolis, Minn. It’s “not normal, based on either observational studies or on computer simulations of the large-scale evolution of the universe,” added the university’s Liliya Williams. ...

Cosmic voids are areas lacking both normal material, such as stars, galaxies and gas, and the mysterious “dark matter” that is also common in the universe. Voids seem to be rarer the bigger they are, astronomers said.
The void sits in a region of the sky in the constellation Eridanus. In addition to being much bigger than any previously-observed void - something over six times the volume of the next biggest - it is also much further away: 6-10 billion light-years versus about one billion light-years.
“We already knew there was something different about this spot,” Rudnick said: it was dubbed the “WMAP Cold Spot,” because it stood out as unusually cold in a map of the background radiation that permeates the cosmos. This radiation - a remnant of the Big Bang explosion thought to have given birth to the universe - was mapped using a satellite called WMAP, for Wilkinson Microwave Anisotropy Probe.
(The phrase "the Big Bang explosion" is actually misleading since nothing actually exploded as with a bomb. The word here should rather be understood in the sense of "very rapid expansion or increase.")

"Cold" in this case refers to the amount of energy in the cosmic background radiation reaching Earth from that part of the sky. Heat is a form of energy, and so the less energy the photons of that radiation have, the "colder" they are. For reasons I won't go into having to do with dark energy (the linked article at World Science goes into it a little), the coldness of that region of space matches up well with the lack of matter in it, so the two observations tend to confirm each other.

That still leaves the question of the existence of this huge void so far away (and so long ago, since the farther away something in space is, the longer it's taken information to reach us and therefore the further back in time that information arose). Examining that question could give greater insight into how our universe came to be the way it is.

Footnote: I have nothing against Kansas, I swear I don't. Well, other than the fact that some idiot regressives there keep trying to get their theology into the study of evolution - but since they keep failing, well, I can forgive that. Until next time.

It's more that I still remember waking up in the morning in Kansas, driving west through unchanging landscape all day, and stopping to rest for the night - still in Kansas.

On the other hand, the state had about the best highway rest stops going: You could park overnight, they had picnic tables with barbecue pits, hot and cold water in the restrooms, they were cool. Maybe I should take a trip back there to see if they're still like that.

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