It is not yet a fully confirmed result, but the faster than light neutrino anomaly appears to have been explained. The culprit? A loose cable. [Science Insider]:
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. Many other physicists suspected that the result was due to some kind of error, given that it seems at odds with Einstein's special theory of relativity, which says nothing can travel faster than the speed of light. That theory has been vindicated by many experiments over the decades.It was always more likely than not that the result would be due to some sort of experimental error. Other measurements showed neutrinos moving at sub-light speeds. Back in the day such measurements were the basis of experiments to determine if neutrinos have mass.
According to sources familiar with the experiment, the 60 nanoseconds discrepancy appears to come from a bad connection between a fiber optic cable that connects to the GPS receiver used to correct the timing of the neutrinos' flight and an electronic card in a computer. After tightening the connection and then measuring the time it takes data to travel the length of the fiber, researchers found that the data arrive 60 nanoseconds earlier than assumed. Since this time is subtracted from the overall time of flight, it appears to explain the early arrival of the neutrinos. New data, however, will be needed to confirm this hypothesis
Experimental physics is hard, often in ways that nobody could expect. One small detail can compromise an experiment people have spent a decade working on.