Experimental Errors Undermine Results
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Lack of energy trail suggests finding was miscalculated By Devin Powell Web edition: October 18, 2011 Print edition: November 5, 2011; Vol.180 #10 (p. 10) A new study puts the brakes on faster-than-light neutrinos. In September, a group at Italy’s OPERA experiment reportedly clocked neutrinos traveling the 730 kilometers from CERN in Switzerland to Italy’s underground Gran Sasso National Laboratory about 60 nanoseconds faster than light would have covered that distance in a vacuum ( SN: 10/22/11, p. 18 ).
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.
Read more: " Neutrinos: Complete guide to the ghostly particle " Faster-than-light neutrinos can't catch a break. If they exist they would not only flout special relativity but also the fundamental tenet that energy is conserved in the universe. This suggests that either the speedy neutrino claim is wrong or that new physics is needed to account for it. In September, physicists with the OPERA experiment in Gran Sasso, Italy, reported that neutrinos had apparently travelled there from CERN near Geneva, Switzerland, faster than light . The claim threatened to blow a hole in modern physics – chiefly Einstein's special theory of relativity, which set the speed of light as the absolute limit for all particles in the universe.
The CERN particle physics laboratory in Geneva has confirmed Wednesday's report that a loose fiber-optic cable may be behind measurements that seemed to show neutrinos outpacing the speed of light. But the lab also says another glitch could have caused the experiment to underestimate the particles' speed. In a statement based on an earlier press release from the OPERA collaboration, CERN said two possible "effects" may have influenced the anomalous measurements. One of them, due to a possible faulty connection between the fiber-optic cable bringing the GPS signals to OPERA and the detector's master clock, would have caused the experiment to underestimate the neutrinos' flight time, as described in the original story . The other effect concerns an oscillator, part of OPERA's particle detector that gives its readings time stamps synchronized to GPS signals.