暗物質(zhì)和暗能量之間展開的“宇宙拔河賽”示意圖：暗物質(zhì)產(chǎn)生收縮力，暗能量產(chǎn)生排斥力；隨著時間的推移，暗能量的力量超越暗物質(zhì)，所以整個宇宙表現(xiàn)為加速膨脹。
ZwCl0024+1652星系團中的環(huán)形暗物質(zhì)
碰撞中的子彈狀星云團所產(chǎn)生的引力透鏡現(xiàn)象
利用超級計算機對部分宇宙進行模擬，所獲得的截面顯示：星系為燈絲狀結(jié)構(gòu)上比較明亮的圓點，大量的暗能量充斥于星系之間。
Greatest Mysteries: Where is the Rest of the Universe?
Scientists trying to create a detailed inventory of all the matter and energy in the cosmos run into a curious problem--the vast majority of it is missing. | 科學(xué)家們企圖為宇宙里的所有物質(zhì)和能量創(chuàng)建一份詳細的列單，卻遇到了一個奇怪的難題：絕大部分物質(zhì)和能量不知去向。 |
"I call it the dark side of the universe," said Michael Turner, a cosmologist at the University of Chicago, referring to the great mysteries of dark matter and dark energy. | 提到暗物質(zhì)和暗能量這些不解之謎時，芝加哥大學(xué)的宇宙學(xué)家邁克爾·特納說：“我管這些叫宇宙的黑暗面?！?/span> |
In fact, only 4 percent of the matter and energy in the universe has been found. The other 96 percent remains elusive, but scientists are looking in the farthest reaches of space and deepest depths of Earth to solve the two dark riddles. | 實際上，目前只發(fā)現(xiàn)了宇宙中4%的物質(zhì)和能量，其余的96%仍然難以捉摸。但是科學(xué)家們正在向太空的最遠處和地球的最深處探望，以期揭開暗物質(zhì)和暗能量的黑暗面紗。 |
Missing matter | 失蹤的物質(zhì) |
Einstein's famous equation "E=mc^2" describes energy and matter (or mass) as one and the same--maps of the cosmos refer to the energy-matter combination as energy density, for short. The problem with detecting dark matter, thought to make up 22 percent of the universe's mass/energy pie, is that light doesn't interact with it. | 愛因斯坦著名的公式E=mc2把能量和物質(zhì)（或質(zhì)量）描述成同一回事，宇宙示意圖中將能量與物質(zhì)的結(jié)合簡稱為能量密度?？茖W(xué)家們認為暗物質(zhì)占整個宇宙總能量的22%，他們在探測暗物質(zhì)方面遇到的問題是：暗物質(zhì)不跟光產(chǎn)生相互作用。 |
But it does exhibit the tug of gravity. | 然而，暗物質(zhì)確實能夠表現(xiàn)出引力。 |
Initial evidence for the mysterious matter was discovered 75 years ago when astrophysicists noticed an anomaly in a jumble of galaxies: The galactic cluster had hundreds of times more gravitational pull than it should have, far outweighing its visible mass of stars. | 這種神秘物質(zhì)的最初證據(jù)是在75年前發(fā)現(xiàn)的。當(dāng)時天體物理學(xué)家們在一個星系團中觀察到一個奇異的現(xiàn)象：星系團的引力是其應(yīng)有引力的幾百倍，遠遠超出了其中可以看到的眾多恒星所產(chǎn)生的引力。 |
"We can predict the motions of the sun and planets very accurately, but when we measure distant things we see anomalies," said Scott Dodelson, an astrophysicist at Fermi National Accelerator Laboratory in Illinois. "Dark matter is currently the best possible solution, even though we've never seen any of it." | 伊利諾斯州費米國家加速器實驗室的天體物理學(xué)家斯科特·多戴爾森說：“我們可以非常精確地預(yù)測太陽和行星的運行情況，可是當(dāng)我們觀測遠處的物質(zhì)時，就會看到異常現(xiàn)象。盡管我們從來都沒有看到過暗物質(zhì)，但暗物質(zhì)卻是目前解決問題的最好辦法?！?/span> |
Another hallmark of dark matter is gravitational lensing, similar to the effect of light passing through a piece of polished glass. Massive objects like the sun can bend light, but colossal clouds of dark matter create "bubbles" in the cosmos that magnify, distort and duplicate the light of galaxies or stars behind them. | 暗物質(zhì)的另一個特征是引力透鏡現(xiàn)象，類似光線通過磨光玻璃時所產(chǎn)生的效果。質(zhì)量巨大的天體如恒星，可以使光線發(fā)生折射，而大團的暗物質(zhì)在宇宙中形成“氣泡”，這種“氣泡”可以加強、扭曲和復(fù)現(xiàn)其后面的星系或恒星所發(fā)出的光線。 |
Gravitational lensing recently exposed evidence of the unseen mass in the Bullet cluster as well as in a ring around a cluster of colliding galaxies called ZwCl0024+1652. |
不久前，引力透鏡現(xiàn)象在碰撞中的星系團ZwCl0024+1652所產(chǎn)生的環(huán)形物中顯現(xiàn)出來，這種現(xiàn)象也曾出現(xiàn)在子彈狀星系團中，證明了這種不可見物質(zhì)是存在的。 |
| Particle hunt | 尋覓粒子 |
| In spite of the ghostly evidence, pieces of dark matter have yet to be pinned down by researchers. "Until we actually discover particles, we're not home yet," Dodelson said. | 盡管存在幽靈般的證據(jù)，但組成暗物質(zhì)的材料究竟是什么，還有待研究人員去搞清楚。多戴爾森指出：“直到真正發(fā)現(xiàn)了組成暗物質(zhì)的粒子，我們才算是搞徹底了。” |
| Particle physicists have detected neutrinos, which are extremely lightweight particles that pour out of the sun and hardly interact into ordinary matter, but Turner said they make up an extremely small fraction of dark matter in the universe. | 粒子物理學(xué)家已經(jīng)發(fā)現(xiàn)了中微子。中微子是從太陽中發(fā)出來的極其輕微的粒子，它們幾乎無法進入任何普通物質(zhì)。然而，特納說中微子僅僅構(gòu)成了宇宙中暗物質(zhì)的極少一部分。 |
| "We arrested one of the members of the gang, but not the leader of the gang," Turner said of neutrinos. He thinks the leader is actually a WIMP: a weakly interactive, massive particle. Unfortunately, WIMPS are just a theory so far. | 提到中微子的時候，特納說：“我們捕捉到這群粒子中的一種，但這并是其中最主要的一種?！彼J為暗物質(zhì)中最主要的粒子實際上是弱作用重粒子。遺憾的是，到目前為止弱作用重粒子僅僅是理論的產(chǎn)物。 |
| The thinking goes that WIMPs are very heavy, yet like neutrinos they rarely bump into matter to produce a detectable signal. But the idea that WIMPS--such as theoretical axion or neutralino particles--can bump into visible matter at all gives scientists hope. | 科學(xué)家們通常認為，弱作用重粒子非常沉重，然而就象中微子一樣不會進入物質(zhì)而產(chǎn)生可以探測到的信號。但是，意識到有些弱作用重粒子，如：理論上的軸子和中性伴隨子，可能會進入可見物質(zhì)，使科學(xué)家們有了希望。 |
| "This is a story that may soon be at its end," Turner said, noting that the Cryogenic Dark Matter Search in the Soudan mine of Minnesota and other experiments below the ground should be sensitive enough to detect a WIMP. | 特納注意到明尼蘇達州蘇丹礦山里的低溫暗物質(zhì)搜尋計劃及其他的地下試驗非常精確靈敏，應(yīng)該可以探測到弱作用重粒子，他說：“情況可能很快就會有結(jié)果的?！?/span> |
| The anti-gravity | 反引力 |
| Perhaps the biggest mystery of all is dark matter's big cousin, dark energy. | 也許最高深莫測之謎當(dāng)屬暗物質(zhì)的近親——暗能量了。 |
| The invisible force is thought to be a large-scale "anti-gravity," pushing apart galactic clusters and causing the unexplainable, accelerating expansion of the universe. Turner thinks dark energy is the biggest mystery of them all--and quite literally, since physicists predict that it makes up 74 percent of energy density in the universe. | 這種不可見的力量被認為是大范圍的“反引力”，它將星系團撕裂開來，導(dǎo)致宇宙莫名其妙地加速膨脹。特納認為，暗能量是所有謎團當(dāng)中最高深莫測之謎。確實如此，因為科學(xué)家們預(yù)測暗能量在宇宙能量密度中占有74%的份額。 |
| "So far, the greatest achievement with dark energy is giving it a name," Turner said of the elusive force. "We are really at the very beginning of this puzzle." | 有關(guān)這種難以捉摸的力量，特納指出：“到目前為止，在暗能量方面所取得的最了不起的成就是為它取了個名字。在解決這個難題方面，我們確實尚處于最初始的階段?！?/span> |
| Turner described dark energy as "really weird stuff," best thought of as an elastic, repulsive gravity that can't be broken down into particles. "We know what it does, but we don't know what it is," Turner said. | 特納將暗能量描述成“真正的怪物”，它最容易使人想到一種不可分解為粒子的、富有彈性的排斥力。特納說：“我們知道暗能量所起的作用，卻不知道它到底是什么?！?/span> |
| While astrophysicists look deep into space to gather more details about dark energy's effects, Turner noted that theoretical physicists are focusing on explaining how the force actually works. And at this point, he joked, any physicist's explanation for dark energy is probably good enough to consider. | 盡管天體物理學(xué)家們把視線指向太空的深邃之處，以獲取有關(guān)暗能量的更多詳細情況，特納卻注意到理論物理學(xué)家們在集中精力解釋暗能量究竟是如何起作用的。對此，特納開玩笑說，大概所有物理學(xué)家們對暗能量的解釋都很妙，均值得考慮。 |
| "We're at this very early stage, at the crime scene of dark energy's existence, if you will," Turner said. "It's a highly creative period, and now is the time for ideas." | 特納指出：“我們的研究還處于最初始的階段，而我們也就在暗能量的包圍圈之中。這也是一個極具創(chuàng)造性的階段，現(xiàn)在正是百家爭鳴的時期?！?/span> |
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