新证据显示宇宙存在未知结构
New Proof Unknown "Structures" Tug at Our Universe Mysterious"dark flow" extends deeper than previously seen.
John Roachfor National Geographic NewsPublished March 22, 2010
"Dark flow" is no fluke, suggests a new study that strengthens the case for unknown, unseen "structures" lurking on the outskirts of creation.
In 2008 scientists reported the discovery of hundreds of galaxy clusters streaming in the same direction at more than 2.2 million miles (3.6 million kilometers) an hour.
This mysterious motion can't be explained by current models for distribution of mass in the universe. So the researchers made the controversial suggestion that the clusters are being tugged on by the gravity of matter outside the known universe.
Now the same team has found that the dark flow extends even deeper into the universe than previously reported: out to at least 2.5 billion light-years from Earth.
After using two additional years' worth of data and tracking twice the number of galaxy clusters, "we clearly see the flow, we clearly see it pointing in the same direction," said study leader Alexander Kashlinsky, an astrophysicist at NASA's Goddard Space Flight Center in Maryland.
"It looks like a very coherent flow."
The find adds to the case that chunks of matter got pushed outside the known universe shortly after the big bang—which in turn hints that our universe is part of something larger: a multiverse.
Dark Flow's Extended Reach
Kashlinsky and colleagues first noticed the dark flow when studying the way gas in galaxy clusters interacts with the cosmic microwave background radiation. This burst of light is thought to have been released just 380,000 years after the big bang and now permeates the universe.
(Related: "Universe 20 Million Years Older Than Thought.")
Data from the Wilkinson Microwave Anisotropy Probe (WMAP) can show the minute temperature changes created as the cosmic microwave background radiation moves through gases in galaxy clusters.
These gases scatter light from the cosmic microwave background radiation as it passes through the clusters, similar to the way Earth's atmosphere can scatter starlight, making some stars twinkle.
But the clusters are also moving relative to the background radiation, so the scattered light gets distorted further by the Doppler effect. This distortion appears in the form of temperature shifts in WMAP data, which can reveal the clusters' direction and speed.
"It is very difficult to isolate for each individual cluster," Kashlinsky said, so the original study had examined 700 clusters.
The new study is based on the collective motion of about 1,400 galaxy clusters, and seeing dark flow with the greater number of clusters gives the researchers more confidence in their result.
In addition, the team tested their analysis method by comparing the x-ray brightness of certain clusters with the strength of temperature changes seen in the WMAP data. Brighter clusters—those with more hot gases—would be expected to have greater affects on the cosmic microwave background, and that's what the new study confirmed.
Kashlinsky speculates that the dark flow extends "all the way across the visible universe," or about 47 billion light-years, which would fit with the notion that the clusters are being pulled by matter that lies beyond known horizons.
Dark flow, he said, "would be much more difficult to explain theoretically if it extended and then just stopped."
Findings are reported in the March 20 issue of The Astrophysical Journal Letters.
来源：美国国家地理http://news.nationalgeographic.com/news/2010/03/100322-dark-flow-matter-outside-universe-multiverse/ 网易有中文版：
http://discover.news.163.com/10/0324/09/62HHHHDV000125LI.html 昏，你又这么干啊，自己不翻译一下？多余的同样帖子就回收了啊，论坛这个速度可太快了。 没时间，趁着程序忙着计算的空当看看新闻，发发贴。 黑暗流和暗物质有无关联？ 网易新闻是垃圾。翻译也不好哦。 也许宇宙并不是唯一的 Dark Flow 翻译为“暗流”比“黑暗流”好得多，多一个字就很不舒服了。“暗流”我不懂，是否就是受到我们视界外宇宙的影响，该是一家之言吧。
这个其实是翻译者本身能力的问题，懂英文还不够，中文要好。 这个观点好象不需要什么证据,
如果出一道题: 宇宙中是否存在未知结构,
不知道会不会有人选择"否", 回复 11# hiblue
至少天文爱好者不会就行了 我以前看过这条新闻。 我总感觉，就算算上人类在地球上生存的极限时间，宇宙也是不可能完全弄清楚的。因为，虽然有一些物理现像可证明宇宙的一些情况，但是无法解释宇宙的来源，那仅仅是种假设。 之前还有科学馆翻译了一条外太空来的电波信号呢。。：这里是第四宇宙，发生大爆炸请求支援...
难道有好多个宇宙？----多元宇宙？那我们现在是在哪个宇宙。。？ 本帖最后由 gohomeman1 于 2010-7-11 16:43 编辑
回复 15# Eiru
你前面的那句话完全是无根据的，以后发言请注意。
关于大行星怎么算清除了轨道周围空间，你可以在知识版发问。 回复 16# gohomeman1
其实我也在书上看来的。。呵呵。
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