太空中神秘而新奇的“暗流”（组图）

太空中神秘而新奇的“暗流”（组图）  

星系团1E 0657-56（被称为子弹状星系团）位于38亿光年之外，好象是神秘的宇宙暗流所推动的几百个星系团之一。

移动的星系团（白点）中的高温气体改变了宇宙微波的温度。几百个遥远的星系团好象正在朝着同一片天区（紫色椭圆区）移动。

Mysterious New 'Dark Flow' Discovered in Space

As if the mysteries of dark matter and dark energy weren't vexing enough, another baffling cosmic puzzle has been discovered.	神秘的暗物质和暗能量好象不足以让人感到困惑，现在又发现了另外一个莫名其妙的宇宙之谜。
Patches of matter in the universe seem to be moving at very high speeds and in a uniform direction that can't be explained by any of the known gravitational forces in the observable universe. Astronomers are calling the phenomenon "dark flow."	宇宙中成团的物质好象正在以极高的速度朝着同一个方向运动，这个现象用可见宇宙中的任何引力模式都无法进行解释，天文学家们称之为“暗流”。
The stuff that's pulling this matter must be outside the observable universe, researchers conclude.	研究人员得出结论说：牵引这种物质流的力量一定来自可见宇宙之外。
When scientists talk about the observable universe, they don't just mean as far out as the eye, or even the most powerful telescope, can see. In fact there's a fundamental limit to how much of the universe we could ever observe, no matter how advanced our visual instruments. The universe is thought to have formed about 13.7 billion years ago. So even if light started travelling toward us immediately after the Big Bang, the farthest it could ever get is 13.7 billion light-years in distance. There may be parts of the universe that are farther away (we can't know how big the whole universe is), but we can't see farther than light could travel over the entire age of the universe.	当科学家们谈及可见宇宙时，他们的意思不仅仅是指眼睛所能看到的，甚至也不局限于利用最具威力的望远镜所能看到的。事实上，不管我们的目视仪器有多么先进，我们所能够观察到的宇宙都有一个基本限度。天文学家们认为，宇宙是大约137亿年以前形成的。因此，即使光线在宇宙大爆炸之后立即朝我们传播，它所穿行的最远距离也不过137亿光年。我们不可能知道整个宇宙到底有多大，也许宇宙中存在更为遥远的区域。但是，光线在宇宙有史以来所传播的全部距离是个极限，我们无法看得更远。
Mysterious motions	神秘的运动
Scientists discovered the flow by studying some of the largest structures in the cosmos: giant clusters of galaxies. These clusters are conglomerations of about a thousand galaxies, as well as very hot gas which emits X-rays. By observing the interaction of the X-rays with the cosmic microwave background (CMB), which is leftover radiation from the Big Bang, scientists can study the movement of clusters.	通过研究宇宙中一些最大的构造——巨型星系团，科学家们发现了暗流。这些星系团是由大约1000个星系以及散发X射线的超高温气体构成的团状构造。通过观察X射线跟宇宙微波背景的相互作用，科学家们可以研究星系团的运动情况。宇宙微波背景指宇宙大爆炸时留下来的辐射。
The X-rays scatter photons in the CMB, shifting its temperature in an effect known as the kinematic Sunyaev-Zel'dovich (SZ) effect. This effect had not been observed as a result of galaxy clusters before, but a team of researchers led by Alexander Kashlinsky, an astrophysicist at NASA's Goddard Space Flight Center in Greenbelt, Md., found it when they studied a huge catalogue of 700 clusters, reaching out up to 6 billion light-years, or half the universe away. They compared this catalogue to the map of the CMB taken by NASA's Wilkinson Microwave Anisotropy Probe (WMAP) satellite.	X射线将光子散播在宇宙微波背景中，结果在一种被称为“运动学SZ效应”的作用下改变了宇宙微波背景的温度。以前，在星系团的研究中没有观察到这种效应。然而，马里兰州格林贝尔特市美国国家航空航天管理局戈达德太空飞行中心的天体物理学家亚历山大·卡什林斯基带领一个研究小组，在研究700个同一类别的巨型星系团时发现了运动学SZ效应。这些星系团位于60亿光年之外，或者说位于宇宙的半空中。他们将这类星系团跟美国国家航空航天管理局的威尔金森微波各向异性探测卫星所绘制的宇宙微波背景图进行了对比。
They discovered that the clusters were moving nearly 2 million mph (3.2 million kph) toward a region in the sky between the constellations of Centaurus and Vela. This motion is different from the outward expansion of the universe (which is accelerated by the force called dark energy).	研究人员发现，这些星系团正在以将近每小时200万英里（320万公里）的速度朝着人马座和船帆座之间的一个天区运动，这种运动跟宇宙向外的膨胀运动不同。宇宙的膨胀在一种叫做“暗能量”的力量作用下呈现出加速状态。
"We found a very significant velocity, and furthermore, this velocity does not decrease with distance, as far as we can measure," Kashlinsky told SPACE.com. "The matter in the observable universe just cannot produce the flow we measure."	“我们发现了一种具有重要意义的速度，并且根据我们的测量这一速度不会随着距离的增加而降低，”卡什林斯基告诉《太空网》的记者说，“可见宇宙中的物质根本不会产生我们所测量到的这种运动流。”
Inflationary bubble	膨胀的气泡
The scientists deduced that whatever is driving the movements of the clusters must lie beyond the known universe.	科学家们推断，驱使这些星系团运动的力量肯定存在于已知宇宙之外。
A theory called inflation posits that the universe we see is just a small bubble of space-time that got rapidly expanded after the Big Bang. There could be other parts of the cosmos beyond this bubble that we cannot see.	一种叫做“膨胀论”的理论提出假设：我们所看到的宇宙不过是时空中的一个小气泡，该气泡在宇宙大爆炸之后迅速膨胀开来。在这个气泡之外，仍然有可能存在我们不能看到的其他宇宙区域。
In these regions, space-time might be very different, and likely doesn't contain stars and galaxies (which only formed because of the particular density pattern of mass in our bubble). It could include giant, massive structures much larger than anything in our own observable universe. These structures are what researchers suspect are tugging on the galaxy clusters, causing the dark flow.	在这些区域里，时空可能大不相同，其中可能不包含恒星和星系，因为恒星和星系只有通过我们的气泡中具有独特密度模式的物质才能够形成。这种时空中可能含有大质量的巨型构造，比我们可见宇宙中的任何构造都要大得多。研究人员认为，这些巨型构造在牵引着星系团运动，产生了暗流。
"The structures responsible for this motion have been pushed so far away by inflation, I would guesstimate they may be hundreds of billions of light years away, that we cannot see even with the deepest telescopes because the light emitted there could not have reached us in the age of the universe," Kashlinsky said in a telephone interview. "Most likely to create such a coherent flow they would have to be some very strange structures, maybe some warped space time. But this is just pure speculation."	“膨胀作用将引起这种运动的构造排斥得异常遥远，我估计可能在数千亿光年之外，即使我们利用最具威力的望远镜也不可能看到，因为那里发出的光线在宇宙的有生之年是不可能到达我们的，”卡什林斯基在一次电话采访中说，“要想产生如此连贯的运动流，这些构造很可能会不得不呈现出极为奇特的结构，也许表现为某种扭曲的时空。但这只是纯粹的推测。”
Surprising find	令人称奇的发现
Though inflation theory forecasts many odd facets of the distant universe, not many scientists predicted the dark flow.	尽管膨胀论预测到遥远的宇宙中有许多奇怪的方面，但是预测到暗流的科学家并不多。
"It was greatly surprising to us and I suspect to everyone else," Kashlinsky said. "For some particular models of inflation you would expect these kinds of structures, and there were some suggestions in the literature that were not taken seriously I think until now."	“这太让我们感到惊讶了，我想任何其他人也都会感到同样惊讶的，”卡什林斯基说，“人们会期待利用这些构造来创建某些特殊的膨胀模型。我认为，文献中的某些建议直到目前才得到重视。”
The discovery could help scientists probe what happened to the universe before inflation, and what's going on in those inaccessible realms we cannot see.	该发现能够帮助科学家们探索在膨胀之前宇宙里曾经发生了什么情况，还会有助于探索在那些无法看到的、不可接近的区域正在发生什么情况。