物理学哲学分享 http://blog.sciencenet.cn/u/赵国求 研究员,武汉市学科带头人,专著十部,国内外发表论文六十余篇。

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IP: 218.60.51.*   [82]沈惠川   2012-2-23 15:07
转载:中微子超光速的最终定论
BREAKING NEWS: Error Undoes Faster-Than-Light Neutrino Results


    It appears that the faster-than-light neutrino results, announced last September by the OPERA collaboration in Italy, was due to a mistake after all. A bad connection between a GPS unit and a computer may be to blame.

    Physicists had detected neutrinos travelling from the CERN laboratory in Geneva to the Gran Sasso laboratory near L’Aquila that appeared to make the trip in about 60 nanoseconds less than light speed. Many other physicists suspected that the result was due to some kind of error, given that it seems at odds with Einstein’s special theory of relativity, which says nothing can travel faster than the speed of light. That theory has been vindicated by many experiments over the decades.
    According to sources familiar with the experiment, the 60 nanoseconds discrepancy appears to come from a bad connection between a fiber optic cable that connects to the GPS receiver used to correct the timing of the neutrinos’ flight and an electronic card in a computer. After tightening the connection and then measuring the time it takes data to travel the length of the fiber, researchers found that the data arrive 60 nanoseconds earlier than assumed. Since this time is subtracted from the overall time of flight, it appears to explain the early arrival of the neutrinos. New data, however, will be needed to confirm this hypothesis.


中微子超光速原因:线没接好!!!!
我的回复(2012-2-23 16:48):谢谢!
.
IP: 222.209.238.*   [81]罗教明   2012-1-22 18:55
龙年吉祥!
IP: 59.174.155.*   [80]赵国求   2012-1-3 10:48
雅默的"量子力学的哲学"很好,你校图书馆应该有.我的那本"从相互作用实在到量子力学曲率解",当当、亚马逊网上有购,可看看。图书馆找到的那本最好换成现在的。
IP: 113.142.17.*   [79]issuense   2012-1-3 01:15
赵老师您好,对量子理论的解释学生也很有兴趣,您的曲率解释我只在图书馆找到一本"物理学的神曲—量子力学的曲率解释"这本书,03年的版本。
能不能麻烦您给学生推荐一些量子论解释的资料?非常感谢!!
IP: 87.93.93.*   [78]甘春梅   2011-12-24 01:20
您好。我是华中师范大学信息管理系的博士生甘春梅。想麻烦您帮我们做一份有关“学术博客知识交流与共享行为”的调查问卷(需要7-8分钟时间,问卷地址:http://www.sojump.com/jq/1201103.aspx)。
        本次调查完全出于学术研究目的,旨在考察个体通过学术博客与他人进行知识交流与共享行为的心理情况。研究的成果将有助于增强您和他人的学术交流与合作,同时也有助于加强对知识管理的深层知识。
        对您的合作和支持,我们表示衷心的感谢!
IP: 59.174.153.*   [77]赵国求   2011-12-16 16:49
已同他讲了,过几天与另一本书一起送.
IP: 221.194.180.*   [76]沈惠川   2011-12-12 16:15
桂起权教授处你去了没有?
我的回复(2011-12-16 16:47):我碰到他了,你送的书讲了,过几天与另一本书一起给.放心.
IP: 59.174.159.*   [75]赵国求   2011-11-28 18:10
正峰:我的博文里有一篇文章简单讨论了这一问题,可先看看。电话里也可以说说。祝全家幸福!
IP: 110.85.190.*   [74]zzf195712   2011-11-28 13:49
叔:好久没来你的“自留地”。我读了一篇文章,感到迷茫,转给您看看。
IP: 59.174.149.*   [73]赵国求   2011-11-27 11:08
知道了。谢谢!
IP: 221.194.180.*   [72]沈惠川   2011-11-27 09:02
评审意见和对原文的修改,已发出。
IP: 220.166.197.*   [71]罗教明   2011-10-14 10:27
祝您生日快乐!
happy birthday to you!

   
.   
我的回复(2011-10-14 12:38):谢谢!谢谢!
IP: 59.174.157.*   [70]赵国求   2011-10-9 17:02
好的,我将认真学习.
IP: 125.39.142.*   [69]沈惠川   2011-10-9 16:34
关于OPERA和中微子的一些消息
    来源是http://physicsworld.com/cws/article/news/47427
    引用李淼微博上的说法“最新消息:声称发现超光速中微子的OPERA合作组出现问题,160多人的合作组有30位领导,在讨论是否将论文投稿时30人中不少人反对,认为需要继续检查系统误差,例如在用实验中产生的光子计时外,还应检查产生带电粒子的时间。此前,30人中就有数位反对公布论文。”




The claim by a team of researchers in Italy that neutrinos can travel faster than the speed of light will require extra checks before being submitted to a peer-reviewed journal. That is the position of a number of researchers in the OPERA collaboration, which announced on 23 September that it had observed superluminal neutrinos travelling from the CERN particle-physics lab near Geneva to the Gran Sasso underground lab in central Italy.

The announcement made headlines around the world, since it appears to contradict Einstein's special theory of relativity. However, not everyone within OPERA was happy to release the results publicly, with several of the 30 group leaders within the 160-strong collaboration being opposed to the release of a paper on the arXiv preprint server and the accompanying seminars and press release without further tests of possible systematic errors being carried out. Now, a larger fraction of the group leaders is concerned about the paper being submitted to a research journal. One member of OPERA, who does not wish to be named, says there is a "lot of tension" within the collaboration and that up to half of the members are opposed to an immediate submission.

Precision measurements
Neutrinos are produced by accelerating protons at CERN's Super Proton Synchrotron accelerator and colliding proton bunches 10 µs in length into a graphite target, generating mesons that in turn decay into neutrinos. The 1300-tonne OPERA detector, which has been running since June 2008, measures the properties of muon neutrinos as they travel 730 km through the Earth's crust from CERN to Gran Sasso.

The experiment was originally designed to study the oscillation of muon neutrinos into tau neutrinos, but following tentative results in 2007 from the MINOS experiment in the US that showed neutrinos appearing to travel faster than light, researchers realized accurate velocity measurements could also be carried out with OPERA. Researchers installed atomic clocks at both ends of the neutrino beam to establish exactly when the neutrinos are created and detected, and used GPS-based measurements to precisely measure the length of the baseline – the velocity being derived by dividing the baseline by the time of flight.

Collecting more than 16,000 events between 2009 and 2011, the OPERA collaboration calculated that muon neutrinos arrive on average 60.7 ns earlier than they would have done had they travelled at the speed of light, which corresponds to a fractional increase over light speed of 25 parts in a million. Having accounted for a host of possible systematic errors, including uncertainties relating to the precise moment of creation and detection of the neutrinos plus errors introduced by cabling and clock synchronization, the researchers arrived at a total systematic error of 7.4 ns, comparable with the statistical error of 6.9 ns.

The OPERA collaboration calculated a confidence level of "6σ", or a one in a billion chance the result was a statistical fluke, and this persuaded most of the collaboration that the result was solid enough to publish. However, some members were worried that unknown sources of systematic error might potentially destroy the confidence level. They argued that before making an announcement, further checks should be carried out – a process that could take several months.



One such check regards the timing of the neutrinos' arrival at Gran Sasso, and involves carrying out an analysis of timing data collected by monitoring the charge, rather than the light, generated by particles passing through the detector. This analysis relies on a very precise and painstaking measurement of the length of the cabling used to collect the timing data, in order to isolate any systematic errors that may be present within the electronics or other parts of the timing system.

Another independent check involves the statistical analysis of the data collected by OPERA. The researchers are not able to track, and therefore time, individual neutrinos as they travel from Geneva to Gran Sasso, but instead they measure the temporal distribution of the protons within each bunch just before the protons hit the graphite target and then compare this with the distribution of the corresponding neutrinos as they are detected in OPERA – with the temporal offset between the two revealing the time of flight. Some members of the collaboration argue that this offsetting procedure needs to be carried out independently, in order to be sure that the temporal profile of the neutrinos leaving CERN can be inferred accurately from that of the protons that produced them.

Heated debate
Discussions about whether or not the collaboration was ready to publish took place in early September. As these discussions were quite animated, the decision was put to a vote, with collaboration spokesperson Antonio Ereditato from the University of Bern proposing that initially the research be published on arXiv while at the same time being presented in a series of scientific seminars, before later being submitted to a peer-reviewed journal. This strategy received a majority, but not a unanimous, vote. It was then left to individual researchers to sign the arXiv paper, with about 10 senior members out of a total of 170 people (including some non-official members) deciding not to do so.

There are so many things that people outside can't check. It is these things that we have to do before publishing
Caren Hagner, Hamburg University
Ereditato says that the collaboration will continue to carry out checks but will do so in parallel with the journal submission. He maintains that no-one outside the collaboration, either at the seminars or via e-mail, has yet presented "smoking guns against what we have seen" and adds that "as experimentalists we have done everything we can". However, Caren Hagner, leader of the OPERA group at Hamburg University and one of the people whose name does not appear on the arXiv paper, believes that the collaboration should carry out the extra checks before submitting the paper for peer review. "Many of the collaboration are convinced that if a mistake is subsequently found it, won't be down to OPERA," she says. "But I am not really convinced. There are so many things that people outside can't check. It is these things that we have to do before publishing."

Laura Patrizii, who is leader of OPERA's Bologna group and who did sign the preprint, clarifies the motivation of the dissenters. "It is not that people think there is a mistake that is being hidden," she says. "But since something going faster than light would kill modern physics as we know it, some researchers would feel more at ease with these independent checks."

Looking to the outside
In addition to the checks that can be carried out within the collaboration, there are also some additional checks that CERN could perform, such as using detectors downstream of the graphite target to provide a better estimate of the profile of the departing neutrinos. The MINOS experiment is also currently improving its cabling and electronics, and collaboration co-spokesperson Jenny Thomas from University College London says that new data collected with the upgraded detector combined with a better analysis of existing data could allow MINOS to largely rule out the OPERA result within the next four to six months (but not to rule it in, given that this would require a higher level of accuracy).

Giovanni Amelino-Camelia, a theoretical physicist at the University of Rome "La Sapienza", believes that a confirmed OPERA result would lead to a "revolution" within physics. But he thinks that this confirmation is unlikely, pointing out that in the history of physics there have been many experimental "alarms" suggestive of a revolution but that only a small fraction of these, such as the Michelson–Morley experiment, have been confirmed.

With OPERA in the spotlight, collaboration members also disagree about their future research programme. Luca Stanco, leader of the OPERA group from the University of Padova and one of the people who did not sign the preprint, believes that the priority now should be further investigation of the superluminal-neutrino result, rather than neutrino oscillations. Ereditato, however, says that even though the collaboration will pursue superluminal research, "the main focus will continue to be oscillations".

About the author
Edwin Cartlidge is a science writer based in Rome



网友调侃

我想起了前段时间的一个段子……
爱因斯坦听说中微子超光速了,猛的从坟墓中坐了起来,然后发现是意大利人做的,于是又放心的躺下了……


额...在这之前我们这里一直都很淡定...还是比较一致的,对于超光速中微子处于根本不信的状态...

意大利人怎么了,没意大利哪来的披萨,哪里来的斜塔
IP: 125.39.142.*   [68]沈惠川   2011-10-2 17:45
相对论的逻辑起点并非光速不变。光速不变只是不得已引入的出发点。
出发点也可以是其他。例如在广义相对论中就换成“等效原理”。
IP: 125.39.142.*   [67]沈惠川   2011-9-29 15:14
给个链接:
http://quantumshen.blogcn.com/
我的回复(2011-10-2 09:19):'极限速度不变',表明论者承认光速不是‘极限速度’,而且小于这个‘极限速度’,我觉得这就够了。因为‘不变的光速’是相对论的逻辑起点。
IP: 218.61.21.*   [66]沈惠川   2011-9-27 17:34
中微子超光速实验估计有问题!
即使实验无误,也有各种可能的解释!
有人认为有“虚质量”,我倒认为“光量子”可能有微小的质量(de Broglie就这么认为的)。
当“光量子”可能有微小的质量时,“光速”就不是极限速度了。另有极限速度。
我的回复(2011-9-28 09:01):谢谢沈老师提供的分析,同意有多种可能解释选项.如同没有必要否定牛顿力学一样,相对论也没有必要否定.它们都有理论建构中的前提约定,离开了前提约定,就无法判定正确与否了.
IP: 218.61.21.*   [65]沈惠川   2011-9-27 07:20
中国科大BBs上转载的文章(方):
CERN-Gran Sasso 的中微子超光速实验

发表于 2011 年 09 月 24 日 由 XXX
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。

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)

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。

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
我的回复(2011-9-27 08:44):谢谢沈老师的资料.
IP: 220.166.194.*   [64]罗教明   2011-9-6 15:25
中秋快乐!
我的回复(2011-9-6 15:27):谢谢!月圆共赏!
IP: 222.201.155.*   [63]吴国林   2011-8-19 12:32
新的论文已发过去

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