Astrophysics
天體物理學
Dust to dust
塵歸塵，土歸土
A dramatic recent 「discovery」 in physics is looking rather dodgy
最近物理學方面的一次戲劇性的「發現」看起來相當撲朔迷離
Sep 27th 2014 | From the print edition of The Economist
譯者：Shevchenko0126
IN MARCH Chao-Lin Kuo, an astrophysicist at Stanford University, filmed himself knocking on the door of his colleague Andrei Linde. In the 1980s Dr Linde was one of several cosmologists who developed the theory of cosmic inflation, which holds that, in the first instants of its existence, the universe underwent a brief period of faster-than-light expansion.
三月份，史丹福大學的一位天體物理學家, Chao-Lin Kuop拍攝了自己敲同事Andrei Linde的門的視頻。在80年代，Linde教授是幾位發現宇宙膨脹理論的宇宙學家之一。這個理論認為，在宇宙出現的一瞬間，宇宙產生一次簡短的超越光速的膨脹。
Because inflation neatly cleaves several knotty problems in cosmology, many astrophysicists (though not all) subscribe to the theory. But direct, unambiguous evidence for it has been lacking. That was why Dr Kuo was visiting Dr Linde—to tell him that, thanks to the work of a telescope in Antarctica called BICEP-2, such evidence had now been found. After digesting the news, an emotional Dr Linde broke open a bottle of champagne to celebrate. The video has been viewed almost 3m times.
因為膨脹這一說法清楚簡單地解釋通了一些宇宙學的難題，許多天體物理學家（儘管不是全部）認可了這一理論。但直截了當地說，關於此理論還缺少毫無爭議的證據來支撐。Kuo博士拜訪Linde博士正是因為要去告訴他，多虧了在南極洲的BICEP-2號望遠鏡的工作，需要的證據如今已經找到了。消化完這個消息後，激動的Linde博士打開了一瓶香檳慶祝。這段視頻已經被瀏覽了3000000次。
It now seems that Dr Kuo might have to make a new video, informing Dr Linde that he has wasted a bottle of bubbly. Apaper just released by the team behind Planck, a European space telescope, casts serious doubt on the BICEP-2 result. What looked like a clear window back into the earliest moments of the universe might simply have been a faint glow from the diaphanous clouds of dust that exist between the stars.
如今Kuo教授也許不得不製作一段新的視頻，通知Linde教授他浪費了一瓶起泡酒。歐洲空間望遠鏡，普朗克的一個團隊剛發表了一份論文，嚴重質疑BICEP-2的結果。那看似是宇宙最早期的影像的也許只是來自於星球之間灰塵雲層的一束微弱的光。
The BICEP-2 team, led by John Kovac of Harvard University, had been studying the cosmic microwave background radiation (CMB)—a weak bath of radiation, left over from the Big Bang, that suffuses the universe. They were looking for evidence of primordial gravitational waves. These are ripples in the fabric of space, created, if the theory of inflation is correct, as the early universe was undergoing its post-creation growth spurt.
哈佛大學的John Kovac，帶領著BICEP-2團隊，一直研究著本底輻射宇宙微波（CMB）,這片微弱的輻射自大爆炸以來充斥著宇宙。他們一直尋找著原始重力波的的證據。這是空間中交織的漣漪。如果膨脹理論是正確的，那麼早期的宇宙確實經歷過宇宙產生階段後的再一次急劇擴增。
A dusty trail
一條塵埃小徑
Such waves should have left a distinctive, polarised mark imprinted upon the CMB. And, in a press conference on March 17th, that is exactly what the BICEP-2 team claimed to have found. It was the biggest news in physics since the discovery, in 2012, of the Higgs boson, and it was widely covered (including in The Economist). Not only would the BICEP result have confirmed the theory of inflation, but studying the gravitational waves it purported to have found would have given cosmologists a way to look back to the very earliest moments of the universe.
這種波動本應該在CMB之上留下獨特的，極化的印記。3月17號的媒體發布會上，這也正是BICEP-2團隊聲稱找到的成果。這是自2012年發現希格斯玻色子之後物理學領域最大的新聞，並被廣泛報導（包含經濟學人雜誌）。不僅BICEP的結果證明了膨脹理論，引力波研究所聲稱的發現也會幫助宇宙學家觀察宇宙最早期時刻。
But gravitational waves are not the only things that BICEP-2 might have picked up. The Milky Way is filled with thin clouds of interstellar dust which, under the influence of the galaxy’s magnetic field, scatter and polarise starlight. The BICEP team were confident that the contamination from the dust was small enough not to affect their detection of gravitational waves. But the behaviour of the dust is poorly understood, says Chris Lintott, an astronomer at Oxford University, and not everyone was convinced.
但是引力波也許並不是BICEP-2團隊僅有的發現成果。銀河中充斥著稀薄的星際塵埃雲，這些塵埃受銀河系的磁場影響，分散並極化星光。BICEP團隊自信來自塵埃的汙染因為規模足夠小並不會影響引力波的觀測。但是塵埃的行跡很難琢磨，牛津大學的天文學家Chris Lintott說道，不是所有人都被說服。
The Planck results suggest that they were right to be sceptical. The European telescope has just unveiled a map of dust density across the entire sky. It suggests that, contrary to the BICEP team’s hopes, the signal from the dust is so strong that the telescope might well have seen no primordial gravity waves at all.
普朗克的結論暗示著之前的結果確實值得懷疑。歐洲望遠鏡只是僅揭示了整片天空中塵埃的密度分布。它表示，與BICEP團隊的願望相反，來自塵埃中的信號太強以至於望遠鏡根本觀測不到最早期的重力波。
That, at least, is the most likely interpretation, but it is not the only one. The Planck team are careful to stop short of saying that their results are fatal to BICEP’s claims, pointing out that applying their data to the BICEP results involves considerable 「statistical and systematic uncertainties」. There are, in other words, a couple of glimmers of hope that signs of inflation have actually been seen. One is that the precise behaviour of the dust is still mysterious, which means the mathematical transformations used to apply Planck’s data to BICEP’s results may turn out to be incorrect. And even if those maths are sound, statistics may ride to the rescue—for if the amount of radiation from the dust is at the lowest end of Planck’s estimates, a small gravitational-wave signal may survive.
這雖不是唯一的解釋，但至少是最可能的了。普朗克團隊很謹慎，並沒有表示自己的觀測結果對於BICEP的結果具有毀滅性打擊，但是指出如果將他們的數據應用到BICEP團隊的結果中，會出現巨大的「統計學的，數據的不確定性」。換句話說，膨脹的表現確實被觀察到的可能性存在一些。有一點是，塵埃的準確運行方式依舊是謎，這也意味著把普朗克的數據運用到BICEP團隊的結果上運用的數學轉換的結果可能並不正確。即使那些數學方式是有作用的，統計學也許會起到作用，如果塵埃中的輻射量處於普朗克估計的最低值，一小部分的重力波將會倖免，從而被觀測到。
Rowing back on a triumphant announcement about the first instants of creation may be a little embarrassing, but the saga is a useful reminder of how science works. There is no suggestion that anyone has behaved dishonourably. Admittedly, the BICEP team’s original press conference looks, with hindsight, seriously overconfident. More information-sharing between the various gravitational wave-hunters, all of whom guard their data jealously, might have helped tone down the triumphalism. But science, ideally, proceeds by exactly this sort of good-faith argument and honourable squabbling—until the weight of evidence forces one side to admit defeat.
回頭看當時宣布發現宇宙產生瞬間時的得意洋洋，會有那麼一點讓人掃興。但是英雄的傳說在提醒我們科學是如何起作用上非常有用。這並不意味著任何人是不值得尊重的。無可否認，馬後炮的角度來看，BICEP團隊最初的媒體發布會看起來確實過度自信了。各隊觀測重力波的團隊充滿猜忌地守衛著他們的數據，如果他們可以彼此分享更多的數據，也許會幫助降低這種必勝主義信念。科學，完美地來說，真是通過這種心懷美好信念的爭執，這種值得尊重的爭吵而進行的，直到有力的證據足以使另一方承認自己失敗。
That could happen soon: the Planck and BICEP teams have pooled their data and are working on a joint paper, expected to be published in the next few months. Information from other gravity-wave hunting experiments—including some run by the BICEP team themselves—will shed extra light, too. It is not yet impossible that Dr Kovac and his colleagues will be proved right after all. But at this point it would take a brave cosmologist to bet on it.
接下來很快會發生：普朗克和BICEP團隊合併數據，共同地致力於一份論文，並且有望於在後幾個月內發表。來自其它重力波探尋試驗的信息——包含一些BICEP團隊自己主持的試驗，也會低調處理。Kovac博士和他的同事們的結論並不是一定會被證明是完全錯的。但是在這點上，也許需要一個勇敢的宇宙學家來下賭注。