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23 september 2011

Faster than light

Researchers from the international accelerator institutes CERN and Gran Sasso have measured particles that move faster than light. They announced that on Friday 23 September during a seminar at CERN, which could be followed via webcast.cern.ch. As this result is highly unexpected and revolutionary in nature, independent measurements from others are now needed. That is why the researchers decided to disclose the results at this stage.
"If this is confirmed then it really will be revolutionary: a completely unexpected and unplanned discovery with enormous implications. In terms of importance this rivals Einstein's theory of relativity. This is what makes curiosity-driven research so much fun! And the actual measurement is almost too simple to explain. That is something you rarely see in my discipline", responds Frank Linde, director of the FOM Institute for Subatomic Physics Nikhef to the latest news from CERN.

The measurement was made as follows: CERN produced a beam of neutrinos and sent these to the Italian OPERA detector 730 km away in the Gran Sasso laboratory. Researchers measured the travel time of the neutrinos. This was found to be 60 nanoseconds faster than light. The researchers admit that a search for systematic errors must now be made. That will in part be done by other accelerator institutes in Japan and the United States. Should the result remain intact then that will be a revolution and exactly what physicists are waiting for: a completely unexpected discovery.

Website Nikhef
Press release CERN
Scientific publication
BBC Online

Update 23 February 2012

CERN press statement
The OPERA collaboration has informed its funding agencies and host laboratories that it has identified two possible effects that could have an influence on its neutrino timing measurement. These both require further tests with a short pulsed beam. If confirmed, one would increase the size of the measured effect, the other would diminish it. The first possible effect concerns an oscillator used to provide the time stamps for GPS synchronizations. It could have led to an overestimate of the neutrino's time of flight. The second concerns the optical fibre connector that brings the external GPS signal to the OPERA master clock, which may not have been functioning correctly when the measurements were taken. If this is the case, it could have led to an underestimate of the time of flight of the neutrinos. The potential extent of these two effects is being studied by the OPERA collaboration. New measurements with short pulsed beams are scheduled for May.

Update 11 June 2012


Neutrinos sent from CERN to Gran Sasso respect the cosmic speed limit
At the 25th International Conference on Neutrino Physics and Astrophysics in Kyoto today, CERN Research Director Sergio Bertolucci presented results on the time of flight of neutrinos from CERN to the Gran Sasso laboratory on behalf of four experiments situated at Gran Sasso. The four, Borexino, ICARUS, LVD and OPERA all measure a neutrino time of flight consistent with the speed of light. This is at odds with a measurement that the OPERA collaboration put up for scrutiny last September, indicating that the original OPERA measurement can be attributed to a faulty element of the experiment’s fibre optic timing system.

"Although this result isn’t as exciting as some would have liked,"
said Bertolucci,"it is what we all expected deep down. The story captured the public imagination, and has given people the opportunity to see the scientific method in action – an unexpected result was put up for scrutiny, thoroughly investigated and resolved in part thanks to collaboration between normally competing experiments. That’s how science moves forward."

Press statement on the CERN website