In September, and again in November, scientists had detected neutrinos travelling from the CERN laboratory in Geneva to the Gran Sasso Laboratory near Rome about 60 nanoseconds faster than a beam of light would have done.
An error was long suspected in the results, which would have contradicted the speed of light as the universe's speed limit, a central tenet of Einstein's theory of special relativity.
Officials at OPERA neutrino experiment now say a fiber optic cable connecting a GPS receiver, used to synchronize the start and arrival times of the neutrinos, and an electronic card in one of the lab computers was found to be loose, LiveScience.com reported Wednesday.
Tightening the connection changed the time it took for data to travel the length of the cable by 60 nanoseconds, which could explain the seemingly early arrival of the neutrinos.
The OPERA team said to confirm this they will have to repeat the experiment now that the fiber optic cable has been secured.