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标题: List下最近比较hot的中微子超光速发现相关文章 [打印本页]

作者: 马丁 时间: 2011-9-26 13:44 标题: List下最近比较hot的中微子超光速发现相关文章

：2011-09-22，日内瓦的CERN (前不久对久被科学界排挤的以色列第一个伸出橄榄枝) 宣称监测到中微子超光速现象。爱因斯坦狭义相对论里说的是任何东东的速度都不可能超过真空中的光速，貌似建立在这上面的理论体系一大堆吧……足够panic了

Source: http://www.telegraph.co.uk/science/8782895/CERN-scientists-break-the-speed-of-light.html
CERN scientists 'break the speed of light'

Scientists said on Thursday they recorded particles travelling faster than light - a finding that could overturn one of Einstein's fundamental laws of the universe.
Link to this video
7:46PM BST 22 Sep 2011
230 Comments

Antonio Ereditato, spokesman for the international group of researchers, said that measurements taken over three years showed neutrinos pumped from CERN near Geneva to Gran Sasso in Italy had arrived 60 nanoseconds quicker than light would have done.

"We have high confidence in our results. We have checked and rechecked for anything that could have distorted our measurements but we found nothing," he said. "We now want colleagues to check them independently."

If confirmed, the discovery would undermine Albert Einstein's 1905 theory of special relativity, which says that the speed of light is a "cosmic constant" and that nothing in the universe can travel faster.

That assertion, which has withstood over a century of testing, is one of the key elements of the so-called Standard Model of physics, which attempts to describe the way the universe and everything in it works.

The totally unexpected finding emerged from research by a physicists working on an experiment dubbed OPERA run jointly by the CERN particle research centre near Geneva and the Gran Sasso Laboratory in central Italy.

作者: 马丁 时间: 2011-9-26 13:44

：实验过程是日内瓦这边打出去的中微子在意大利那边接收，两个地方相距730公里，中微子跑得比预想中稍微快了一点，跌碎了一地的眼镜片。
However，这次测量要用到的GPS常规uncertainty在10纳秒以上，其他人质疑其实验系统误差。

Source: http://news.sciencemag.org/scien ... aster-than-lig.html
Neutrinos Travel Faster Than Light, According to One Experiment
by Adrian Cho on 22 September 2011, 2:28 PM | 79 Comments

Fat lady singing? The OPERA particle detector may have spotted neutrinos traveling faster than light, which would bring down the curtain on special relativity as an exact theory.
Credit: OPERA collaboration

If it's true, it will mark the biggest discovery in physics in the past half-century: Elusive, nearly massless subatomic particles called neutrinos appear to travel just faster than light, a team of physicists in Europe reports. If so, the observation would wreck Einstein's theory of special relativity, which demands that nothing can travel faster than light.

In fact, the result would be so revolutionary that it's sure to be met with skepticism all over the world. "I suspect that the bulk of the scientific community will not take this as a definitive result unless it can be reproduced by at least one and preferably several experiments," says V. Alan Kostelecky, a theorist at Indiana University, Bloomington. He adds, however, "I'd be delighted if it were true."

The data come from a 1300-metric-ton particle detector named Oscillation Project with Emulsion-tRacking Apparatus (OPERA). Lurking in Italy's subterranean Gran Sasso National Laboratory, OPERA detects neutrinos that are fired through the earth from the European particle physics laboratory, CERN, near Geneva, Switzerland. As the particles hardly interact at all with other matter, they stream right through the ground, with only a very few striking the material in the detector and making a noticeable shower of particles.

Over 3 years, OPERA researchers timed the roughly 16,000 neutrinos that started at CERN and registered a hit in the detector. They found that, on average, the neutrinos made the 730-kilometer, 2.43-millisecond trip roughly 60 nanoseconds faster than expected if they were traveling at light speed. "It's a straightforward time-of-flight measurement," says Antonio Ereditato, a physicist at the University of Bern and spokesperson for the 160-member OPERA collaboration. "We measure the distance and we measure the time, and we take the ratio to get the velocity, just as you learned to do in high school." Ereditato says the uncertainty in the measurement is 10 nanoseconds.

However, even Ereditato says it's way too early to declare relativity wrong. "I would never say that," he says. Rather, OPERA researchers are simply presenting a curious result that they cannot explain and asking the community to scrutinize it. "We are forced to say something," he says. "We could not sweep it under the carpet because that would be dishonest." The results will be presented at a seminar tomorrow at CERN.

The big question is whether OPERA researchers have discovered particles going faster than light, or whether they have been misled by an unidentified "systematic error" in their experiment that's making the time look artificially short. Chang Kee Jung, a neutrino physicist at Stony Brook University in New York, says he'd wager that the result is the product of a systematic error. "I wouldn't bet my wife and kids because they'd get mad," he says. "But I'd bet my house."

Jung, who is U.S. spokesperson for a similar experiment in Japan called T2K, says the tricky part is accurately measuring the time between when the neutrinos are born by slamming a burst of protons into a solid target and when they actually reach the detector. That timing relies on the global positioning system, and the GPS measurements can have uncertainties of tens of nanoseconds. "I would be very interested in how they got a 10-nanosecond uncertainty, because from the systematics of GPS and the electronics, I think that's a very hard number to get."

No previous measurements obviously rule out the result, says Kostelecky, who has spent 25 years developing a theory, called the standard model extension, that accounts for all possible types of violations of special relativity in the context of particle physics. "If you had told me that there was a claim of faster-than-light electrons, I would be a lot more skeptical," he says. The possibilities for neutrinos are less constrained by previous measurements, he says.

Still, Kostelecky repeats the old adage: Extraordinary claims require extraordinary evidence. Even Ereditato says that one measurement does not extraordinary evidence make.
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作者: 马丁 时间: 2011-9-26 13:47

本帖最后由马丁于 2011-9-26 18:50 编辑

：有个据说暌违已久的名字闪耀了下，这是他的blog文章

source: http://fang-lizhi.hxwk.org/
CERN-Gran Sasso 的中微子超光速实验
发表于 2011 年 09 月 24 日由方励之

从昨天（09/22/2011）旁晚开始，物理界好像炸了锅，疯传一则消息：CERN （日内瓦）和Gran Sasso  （巨岩，意大利）的中微子实验发现，中微子的传播速度超过光速！今天纽约时报等大小报纸也跟着凑热闹：二十世纪最有名的物理公式，

E=mc2

中的c 不是常数了！似乎爱因斯坦就要完蛋了！

别忙着下结论，先看一下CERN 和Gran Sasso  到底干了什麼。

CERN 和Gran Sasso  两个实验室我都去过。前者拥有世界最大的粒子加速器，后者是世界最大的地下的粒子和天体物理实验室。CERN – Gran Sasso  的中微子实验，想法很简单，如图1所示，在日内瓦的CERN（图左边）产生一束中微子，射向意大利的Gran Sasso  （图右边）。他们测量中微子从CERN  飞到Gran Sasso的时间，又知道，CERN  到Gran Sasso的距离，就测得中微子的飞行速度了。

图1：  虚线是中微子从  CERN  到Gran Sasso  传播途径

由于地球是球状的，中微子从  CERN  到Gran Sasso  的直线传播途径都在地下。中微子可在地球中自由穿行，如入无人之境。中微子传播途径（图1的虚线）对应的地面上，有许多有名的地方：勃朗峰（阿尔卑斯山的最高峰），Piemonte  （葡萄名酒产地），佛罗伦萨（文艺复兴的源点），Arezzo （著名电影“美丽人生”的故事背景所在地，影片在戛纳电影节试映时，全体观众起立鼓掌长达12分钟之久，个个含泪步出影院。它是我看过的所有二战影片中，最好的）……

中微子地下直线穿行距离732公里，根据中微子在CERN的发射时间和在Gran Sasso 接受时间，就可求出中微子的穿行速度。该实验团队宣称，中微子的穿行速度比标准的光速（299792458  米/秒）大 0.0025%。昨晚，他们的论文已在网上贴出（见arXiv：1109.4897v1），题目是“Measurement of the neutrino velocity with the OPERA detector”，作者共174人，来自大小诸国。在大国中，有法，意，日，德，俄，没有美，英，中。

直到写此文的时候，同行对CERN – Gran Sasso 结果的态度，似乎持保留或观望的居多（当然，我是在美国的统计）。

原因之一是，它与超新星1978A 的观测结果矛盾。超新星爆发时会产生强光及中微子。1978A爆发时，小柴昌俊,（Masatoshi Koshiba，获2002年物理诺奖）的地下中微子实验室接受到了中微子信号。而且，中微子信号到达时间几乎同1978A的光信号几乎一样。由于1978A距地球约17万光年，如果光速度与中微子速度哪怕只有极小（10-9）的差别，中微子信号也不可能与光信号同时到达地球。跑得快者先到，慢者后到。而CERN – Gran Sasso 结果是光速度与中微子速度有10-5 的差别。果如此，光信号将比中微子信号晚很多年。

所以，还不忙接受CERN – Gran Sasso 的结果。

等等看， CERN – Gran Sasso 的中微子实验结果能否被其他独立的实验证实。日本的超级神冈探测器，美国费米实验室的设备，都可能重复做类似的实验。

有人已经急着建立新理论了，说中微子速度之所以比光快，是因为中微子走了（高维空间中的）捷径云云。暂时不必当真。

1987年，Gran Sasso 实验室正在建设时，我去过一次。Gran Sasso 实验室建在Gran Sasso 山底部。它由三个大山洞组成。山洞之间有隧道相通。与外界联系也是隧道  （图2）

图2：Gran Sasso 实验室的示意图。它由三个实验室山洞和隧道组成。隧道可通汽车。

Gran Sasso 实验室由意大利修公路的公司承建。意大利的高速公路，山洞极多。给实验室挖几个山洞，不在话下。听说，贵州的高速公路也是意大利公司承建，因为山洞极多。

2006 年，当CERN  – Gran Sasso  中微子实验在建设时，我又去过 Gran Sasso  (图3)。从照片可以看到山洞实验大厅的规模，CERN-Gran Sasso 中微子实验的终端探测器OPERA （The Oscillation Project with Emulsion-tRacking Apparatus），即建于此大厅里。OPERA这个名字是着意取的，不懂一点威尔弟，普契尼，大概很难混进OPERA 团队。

图3: 2006年我和同事访问CERN-Gran Sasso 中微子实验山洞。

Gran Sasso 是风景旅游胜地（图4）。但在 Gran Sasso实验室里工作，却极为单调烦闷，因为环境孤立。只有在孤立安静的环境中才有可能探测到中微子的微弱信号。在 Gran Sasso实验室，常常雇人来做单

图4，Gran  Sasso  景观

调烦闷的工作，但工资不菲。九十年代时，Gran Sasso实验室一直雇有这类中国雇员。他们大多是中国科学院的年轻研究人员。现在几乎没有了，或雇不到了，因为中国科学院的工资也不菲了。

9/23/ 2011, Tucson
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作者: 马丁 时间: 2011-9-26 13:49 标题: [zz]圣斗士的笑话 from 水木

本帖最后由马丁于 2011-9-26 18:50 编辑

[zz]圣斗士的笑话 from 水木
楼主 greyp (放下剑就无法保护你，拿起剑就不能拥抱你)
“受死吧！”艾奥里亚一拳挥出，如电过长空，快捷无伦。然而距离星矢的身体还有毫厘，
就被一股无形的巨力无情地击中了腹部，像落叶一样坠地。“不可能！”艾奥里亚惊恐地叫
道，“你一个区区青铜战士，怎么可能打中我？”“要与时俱进，”星矢笑道，“我这天马中
微子拳自然比你的闪电光速拳更快。”

作者: 马丁 时间: 2011-9-26 13:51

作者: leinlee 时间: 2011-9-26 19:54

圣斗士的笑话，呵呵
搞物理和数学的脑袋都得特殊构造才行啊

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