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.
Even as OPERA was sorting its own problems out, however, other neutrino experiments jumped at the chance to tell them their results were wrong. One of these was MINOS, which uses protons from the Tevatron's accelerator chain to produce neutrinos that are detected in a mine in Minnesota. It had seven years of data to work with, but hadn't been tracking the timing that carefully while gathering it. According to a short article at Fermilab Today, the MINOS team worked with the National Institute of Standards and Technology to nail down the timing of recent events, then used that information to analyze their past work.
The end result was an arrival time consistent with the speed of light within experimental error. And that experimental error was about half the size of the original speed difference spotted by OPERA. Combined, all of this should put the OPERA results to rest. So, all the researchers gathered in Japan can now shift back to focusing on all the strange things that neutrinos actually do.