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CERN Finds Flaws in "Faster-Than-Light" Neutrino Tests
Remember those faster-than-light neutrinos? Scientists at CERN have detected two possible errors that may have produced the unbelievable results of an experiment that, if correct, would have given all of physics a panic attack.
The results of the original experiment were announced in September 2011, after a neutrino beam fired from the CERN particle accelerator appeared to show particles traveling 60 nanoseconds faster than the speed of light. The team behind the results (OPERA) submitted their findings to the scientific community for verification. They responded with understandable skepticism.
Then, a second experiment at the same facility replicated the results of the first. But the new possible errors announced this week would explain both results. As was speculated earlier, the errors have to do with CERN's unestablished use of GPS to synchronize clocks at either end of the beam. Nature explains:
Meanwhile, as the BBC notes, experiments are underway at the Fermilab in the United States, in Japan's T2K facility, and at CERN led by other teams to try and replicate the results. The findings of those experiments should be announced in the next few months.
The results of the original experiment were announced in September 2011, after a neutrino beam fired from the CERN particle accelerator appeared to show particles traveling 60 nanoseconds faster than the speed of light. The team behind the results (OPERA) submitted their findings to the scientific community for verification. They responded with understandable skepticism.
Then, a second experiment at the same facility replicated the results of the first. But the new possible errors announced this week would explain both results. As was speculated earlier, the errors have to do with CERN's unestablished use of GPS to synchronize clocks at either end of the beam. Nature explains:
First, the passage of time on the clocks between the arrival of the synchronizing signal has to be interpolated and OPERA now says this may not have been done correctly. Second, there was a possible faulty connection between the GPS signal and the OPERA master clock.
While the first error may have affected the results, the second could account specifically for the unbelievable results. In fact, after the faulty wiring was fixed, scientists found that data traveling the length of the fiber arrived exactly 60 nanoseconds earlier than before, says Science Insider, who broke the story. According to OPERA, the two possible errors would have opposite effects on the results, so they're reserving judgment until they repeat the experiment again.Meanwhile, as the BBC notes, experiments are underway at the Fermilab in the United States, in Japan's T2K facility, and at CERN led by other teams to try and replicate the results. The findings of those experiments should be announced in the next few months.
Nature News Blog
Faster-than-light neutrino measurement has two possible errors
22 Feb 2012 | 22:49 GMT | Posted by Eugenie Samuel Reich | Category: Physics & Mathematics
The OPERA collaboration, which made headlines in September with the revolutionary claim to have clocked neutrinos traveling faster than the speed of light, has identified two possible sources of error in its experiment. If true its result would have violated Einstein’s Special Theory of Relativity, a cornerstone of modern physics.
OPERA had collected data suggesting that neutrinos generated at CERN near Geneva and sent 730 kilometers to its detector Gran Sasso National Laboratory were arriving 60 nanoseconds faster than a light beam would take to travel the same distance. Many physicists were skeptical but the measurement appeared to be carefully done and reached a statistically significant level.
But according to a statement OPERA began circulating today, two possible problems have now been found with its set-up. As many physicists had speculated might be the case, both are related to the experiment’s pioneering use of Global Positioning System (GPS) signals to synchronize atomic clocks at each end of its neutrino beam. First, the passage of time on the clocks between the arrival of the synchronizing signal has to be interpolated and OPERA now says this may not have been done correctly. Second, there was a possible faulty connection between the GPS signal and the OPERA master clock.
An anonymously sourced account on Science Insider today broke the news that OPERA may have made a mistake . That report says the faulty connection can account exactly for the 60 nanosecond effect. OPERA’s official statement stops short of that, saying instead that its two possible sources of error point in opposite directions and it is still working things out. Its statement reads in full:
“The OPERA Collaboration, by continuing its campaign of verifications on the neutrino velocity measurement, has identified two issues that could significantly affect the reported result. The first one is linked to the oscillator used to produce the events time-stamps in between the GPS synchronizations. The second point is related to the connection of the optical fiber bringing the external GPS signal to the OPERA master clock.
These two issues can modify the neutrino time of flight in opposite directions. While continuing our investigations, in order to unambiguously quantify the effect on the observed result, the Collaboration is looking forward to performing a new measurement of the neutrino velocity as soon as a new bunched beam will be available in 2012. An extensive report on the above mentioned verifications and results will be shortly made available to the scientific committees and agencies.â€
Caren Hagner, a member of OPERA at the University of Hamburg in Germany, says “For the moment the collaboration decided not to make a quantitative statement, because we have to recheck and discuss the findings more thoroughly.â€
At Fermilab, members of the MINOS collaboration (Main Injector Neutrino Oscillation Search) continue to try to make their own independent measurement of the speed of neutrinos, with initial results expected later this year.
Faster-than-light neutrino measurement has two possible errors
22 Feb 2012 | 22:49 GMT | Posted by Eugenie Samuel Reich | Category: Physics & Mathematics
The OPERA collaboration, which made headlines in September with the revolutionary claim to have clocked neutrinos traveling faster than the speed of light, has identified two possible sources of error in its experiment. If true its result would have violated Einstein’s Special Theory of Relativity, a cornerstone of modern physics.
OPERA had collected data suggesting that neutrinos generated at CERN near Geneva and sent 730 kilometers to its detector Gran Sasso National Laboratory were arriving 60 nanoseconds faster than a light beam would take to travel the same distance. Many physicists were skeptical but the measurement appeared to be carefully done and reached a statistically significant level.
But according to a statement OPERA began circulating today, two possible problems have now been found with its set-up. As many physicists had speculated might be the case, both are related to the experiment’s pioneering use of Global Positioning System (GPS) signals to synchronize atomic clocks at each end of its neutrino beam. First, the passage of time on the clocks between the arrival of the synchronizing signal has to be interpolated and OPERA now says this may not have been done correctly. Second, there was a possible faulty connection between the GPS signal and the OPERA master clock.
An anonymously sourced account on Science Insider today broke the news that OPERA may have made a mistake . That report says the faulty connection can account exactly for the 60 nanosecond effect. OPERA’s official statement stops short of that, saying instead that its two possible sources of error point in opposite directions and it is still working things out. Its statement reads in full:
“The OPERA Collaboration, by continuing its campaign of verifications on the neutrino velocity measurement, has identified two issues that could significantly affect the reported result. The first one is linked to the oscillator used to produce the events time-stamps in between the GPS synchronizations. The second point is related to the connection of the optical fiber bringing the external GPS signal to the OPERA master clock.
These two issues can modify the neutrino time of flight in opposite directions. While continuing our investigations, in order to unambiguously quantify the effect on the observed result, the Collaboration is looking forward to performing a new measurement of the neutrino velocity as soon as a new bunched beam will be available in 2012. An extensive report on the above mentioned verifications and results will be shortly made available to the scientific committees and agencies.â€
Caren Hagner, a member of OPERA at the University of Hamburg in Germany, says “For the moment the collaboration decided not to make a quantitative statement, because we have to recheck and discuss the findings more thoroughly.â€
At Fermilab, members of the MINOS collaboration (Main Injector Neutrino Oscillation Search) continue to try to make their own independent measurement of the speed of neutrinos, with initial results expected later this year.
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