This week, the XXV International Conference on Neutrino Physics and Astrophysics (better known as Neutrino 2012) is taking place in Japan, and a number of announcements have been made in association with the meeting. Neutrinos have some fascinating properties (which we’ll discuss at length this weekend), but it’s now clear there is one exceptional feature they lack: the ability to go faster than light. Even the detector that originally reported this finding now agrees that the results were an artifact.
This morning, CERN updated its press release that dates back to the original results, indicating that the four different detectors on the receiving end of its neutrino beam—Borexino, ICARUS, LVD, and OPERA, all located in Italy’s Gran Sasso facility—generated timing results that were consistent with the neutrinos traveling at the speed of light. The inability to discern a difference between the speed of neutrinos and photons is the product of the neutrinos’ extremely tiny mass. A proton is 10,000,000,000 times more massive, so it takes substantially less energy to get a neutrino up to speeds where the distance to the speed of light is just a rounding error.
This appears to confirm that the results were the product of an improperly seated optical cable in the OPERA experiment, which introduced a small but significant timing delay. Those of you who are interested in the technical details of what went wrong may want to read Matt Strassler’s extensive discussion of how this problem was found, and why it could produce the timing problem.