Traces of 'dark matter' discovered 2,000ft below the ground
By David Derbyshire
Last updated at 8:08 PM on 11th February 2010
Discovery: Scientists believe they have found particles of 'dark matter', illustrated here in a computer-generated image (the 'dark matter' is in pink)發現：科學家們相信他們已經找到'暗物質'的粒子，在這裡畫出的是電腦產生的影像（'暗物質'是粉紅色）
Scientists may have caught their first ever glimpse of "dark matter" - the mysterious, invisible substance that makes up three quarters of the matter of the universe.
科學家可能已經有史以來首次瞥見了“暗物質” - 神秘的、看不見的物質，構成了四分之三的宇宙物質。
Traces of two "dark matter particles" were picked up by highly sensitive detectors buried 2,000 ft below the ground at the bottom of an old iron mine, researchers report today.
追踪兩粒“暗物質粒子”是由高度敏感的探測器埋藏在地下二千呎，在一個老鐵礦的底部，研究人員今天報告。
The scientists say there is a three in four chance that the observations are genuine particles of dark matter, rather than just background noise.
科學家們說機會有四份三，觀察到真實的暗物質粒子，而不只是背景噪音。
Dark matter is one of the big mysteries of physics and its discovery would be one of the greatest scientific breakthroughs of the last 100 years.
暗物質是物理學上其中一個大奧秘，和它的發現將是過去 100年一個最偉大的科學突破。
In the 1930s astronomers first realised that the stars, gas and dust only made up a fraction of the matter of the universe. They concluded that galaxies would fall apart unless they were held in place by the gravitational pull of some vast, invisible substance.
For more than 80 years, scientists have debated what this dark matter could be and why we can't see it.
One of the most likely candidates is a tiny object called a "weakly interactive massive particle" or Wimp which bombards the earth from space
Researchers have been looking for traces of Wimps for the last nine years at the bottom of a disused Soudan iron mine in Minnesota.
The experiment uses 30 detectors, frozen to minus 273.1C designed to spot the traces of Wimps after they have bounced into an ordinary atom.
The experiment is buried so deep because Wimps - unlike particles from space - can pass straight through the thick layers of earth and rock.
The researchers report in the journal Science that they have spotted two traces of Wimps. However, they need to find more before they can be certain they have found the elusive dark matter particle.
Dr Tarek Saab, from the University of Florida at Gainesville, said: 'Many people believe we are extremely close - not just us, but other experiments. It is expected or certainly hoped that in the next five years or so, someone will see a clear signal.'
But he acknowledged the current evidence was not quite strong enough.
'With one or two events, it's tough,' he said. 'The numbers are too small.'
http://www.dailymail.co.uk/sciencetech/article-1250306/Traces-dark-matter-discovered-2-000-ft-ground.html
科學家礦場發現暗黑物質
2009年12月19日
當我們抬頭仰望星空時，所看見的其實只是整個宇宙的 4%，宇宙其餘 3/4的組成部份，是傳說中的暗黑物質（ dark matter）。美國科學家聲稱在明尼蘇達州一個深 800米的廢棄鐵礦場，發現到暗黑物質，若測試結果證實屬實，將是物理學在近 76年來最驚人的發現。
研究員利用高靈敏度偵測器，收集到兩個符合所有暗黑物質特性的粒子，現在只待測試結果作實，但有科學家指出，他們的發現，有 1/4機會是由地下偵測器的影響所致，並非真正的暗黑物質。
暗黑物質的討論始於 1933年，但目前我們對它仍所知不多，科學家普遍認為，暗黑物質是不發光的物質，但有顯著的引力效應，宇宙的星體就是全靠暗黑物質的引力，才能聚集一起。
科學家希望今次的發現，有助人類解開為何普通物質不帶放射性，以及時間永遠向前等謎團。
英國《衞報》
http://hk.apple.nextmedia.com/template/apple/art_main.php?iss_id=20091219&sec_id=15335&subsec_id=15339&art_id=13541288
科學家在銀河深處發現暗物質粒子証據
沒有留言:
發佈留言