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In 2011, the OPERA experiment mistakenly observed neutrinos appearing to travel faster than light. Even before the mistake was discovered, the result was considered anomalous because speeds higher than that of light in a vacuum are generally thought to violate special relativity, a cornerstone of the modern understanding of physics for over a century. OPERA scientists announced the results of the experiment in with the stated intent of promoting further inquiry and debate. Later the team reported two flaws in their equipment set-up that had caused errors far outside their original confidence interval: a fiber optic cable attached improperly, which caused the apparently faster-than-light measurements, and a clock oscillator ticking too fast.〔Strassler, M. (2012) ("OPERA: What Went Wrong" ) ''profmattstrassler.com''〕 The errors were first confirmed by OPERA after a ScienceInsider report; accounting for these two sources of error eliminated the faster-than-light results. In March 2012, the collocated ICARUS experiment reported neutrino velocities consistent with the speed of light in the same short-pulse beam OPERA had measured in November 2011. ICARUS used a partly different timing system from OPERA and measured seven different neutrinos. In addition, the Gran Sasso experiments BOREXINO, ICARUS, LVD and OPERA all measured neutrino velocity with a short-pulsed beam in May, and obtained agreement with the speed of light.〔 On June 8, 2012 CERN research director Sergio Bertolucci declared on behalf of the four Gran Sasso teams, including OPERA, that the speed of neutrinos is consistent with that of light. The press release, made from the 25th International Conference on Neutrino Physics and Astrophysics in Kyoto, states that the original OPERA results were wrong, due to equipment failures. On July 12, 2012 OPERA updated their paper by including the new sources of errors in their calculations. They found agreement of neutrino speed with the speed of light. == Detection == The experiment created a form of neutrinos, muon neutrinos, at CERN's older SPS accelerator, on the Franco–Swiss border, and detected them at the LNGS lab in Gran Sasso, Italy. OPERA researchers used common-view GPS, derived from standard GPS, to measure the times and place coordinates at which the neutrinos were created and detected. As computed, the neutrinos' average time of flight turned out to be less than what light would need to travel the same distance in a vacuum. In a two-week span up to , the OPERA team repeated the measurement with a different way of generating neutrinos, which helped measure travel time of each detected neutrino separately. This eliminated some possible errors related to matching detected neutrinos to their creation time. The OPERA collaboration stated in their initial press release that further scrutiny and independent tests were necessary to definitely confirm or refute the results. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Faster-than-light neutrino anomaly」の詳細全文を読む スポンサード リンク
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