:: NEWS COCKTAIL aka BlahBlahBlog ::
"Everything is being compressed into tiny tablets. You take a little pill of news every day - 23 minutes - and that's supposed to be enough." -Walter Cronkite, RE TV news. The Web has changed that for many, however, and here is an extra dose for your daily news cocktail. This prescription tends to include surveillance and now war-related links, along with the occasional pop culture junk and whatever else seizes my attention as I scan online news sites.:: 12.16.2008 ::
:: Dark Energy Stunts Galaxies’ Growth ::
By DENNIS OVERBYE
The New York Times
The same mystery force that is speeding up the expansion of the universe is also stunting the growth of the objects inside it, astronomers said on Tuesday.
After bulking up rapidly in the first 10 billion years of cosmic time, clusters of galaxies, the cloudlike swarms that are the largest conglomerations of matter in the universe, have grown anemically or not at all during the last five billion years, like sullen teenagers who suddenly refuse to eat.
"This result could be explained as arrested development of the universe," said Alexey Vikhlinin of the Harvard-Smithsonian Center for Astrophysics, who led a multinational team using NASA’s Chandra X-ray Observatory to weigh galaxy clusters from far across space. The group reported the results in two papers that will appear in the Astrophysical Journal.
The culprit, he said, appears to be an antigravitational force that astronomers have labeled "dark energy." It was discovered 10 years ago by astronomers who were using exploding stars called supernovas as distance markers to chart the expansion of the universe. In a puzzle that is still reverberating, they found that instead of slowing down because of cosmic gravity, as common sense would suggest, the expansion of the universe was actually speeding up, with galaxies zooming apart faster and faster.
Dr. Vikhlinin’s results dovetail eerily with the supernova results, suggesting that dark energy emerged as a dominant force in the universe about seven billion to five billion years ago. Clusters grow by gravity, according to cosmological theory, starting as small dimples in the heat and fizz of the Big Bang and then drawing in surrounding material over the eons. Dark energy would work against gravity and try to push the matter falling in back out, stalling growth.
Together with earlier observations of supernovas and other effects, Dr. Vikhlinin said, the new data strengthen the suspicion — but do not prove — that dark energy is the result of a weird antigravity called the cosmological constant that was hypothesized and then abandoned by Albert Einstein as a "blunder" almost a century ago.
Many other theories are still in contention, but some that involve modifying Einstein’s general theory of relativity, which has been the last work on gravity for almost a century, might be on the verge of extinction, astronomers said.
"If this was a fox hunt and dark energy was the fox, I think they have closed off another escape route. But there is still a lot of terrain left for the fox, and we’ve seen little more than a glimmer of fur," said Adam Riess, of Johns Hopkins and the Space Telescope Science Institute, and one of the original discoverers of dark energy.
Other astronomers hailed the work as opening a new avenue in the investigation of what is happening and will happen to the cosmos.
Read more here.
A L S O
New Technique Allows Researchers to Measure Dark Energy
Washington Post
Dark Energy = Einstein's Cosmological Constant?
Wired News
Dark energy, which forms almost three-quarters of the universe, is the most mysterious stuff known to man. A new set of Chandra X-Ray Observatory data, however, has given scientists good information on what dark energy might actually be.
Turns out, it looks suspiciously like Einstein's cosmological constant, a factor he added to his theory of general relativity. He once considered it his greatest blunder.
posted by me
:: 5:07:00 PM [+] ::
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