2011 OPERA faster-than-light neutrino anomaly

Fig. 1 Faster than light neutrinos. What OPERA saw. Leftmost is the proton beam from the CERN SPS accelerator. It passes the beam current transformer (BCT), hits the target, creating first, pions and then, somewhere in the decay tunnel, neutrinos. The red lines are the CERN Neutrinos to Gran Sasso (CNGS) beam to the LNGS lab where the OPERA detector is. The proton beam is timed at the BCT. The left waveform is the measured distribution of protons, and the right that of the detected OPERA neutrinos. The shift is the neutrino travel time. Distance traveled is roughly 731 km. At the top are the GPS satellites providing a common clock to both sites, making time comparison possible. Only the PolaRx GPS receiver is above-ground, and fiber cables bring the time underground.
Fig. 1 What OPERA saw. Leftmost is the proton beam from the CERN SPS accelerator. It passes the beam current transformer (BCT), hits the target, creating first, pions and then, somewhere in the decay tunnel, neutrinos. The red lines are the CERN Neutrinos to Gran Sasso (CNGS) beam to the LNGS lab where the OPERA detector is. The proton beam is timed at the BCT. The left waveform is the measured distribution of protons, and the right that of the detected OPERA neutrinos. The shift is the neutrino travel time. Distance traveled is roughly 731 km. At the top are the GPS satellites providing a common clock to both sites, making time comparison possible. Only the PolaRx GPS receiver is above-ground, and fiber cables bring the time underground.

In 2011, the Oscillation Project with Emulsion-tRacking Apparatus (OPERA) experiment mistakenly observed neutrinos appearing to travel faster than light. Even before the source of the error was discovered, the result was considered anomalous because speeds higher than that of light in vacuum are generally thought to violate special relativity, a cornerstone of the modern understanding of physics for over a century.[1][2]

On June 8, 2012, after further research and analysis, CERN research director Sergio Bertolucci declared that the speed of neutrinos is consistent with that of light. The press release, made from the 25th International Conference on Neutrino Physics and Astrophysics in Kyoto, states that the original OPERA results were wrong, due to equipment failures.[3]

On July 12, 2012, OPERA updated their paper by including the new sources of errors in their calculations. They found agreement of neutrino speed with the speed of light.[4]

  1. ^ Reich (2011b).
  2. ^ Many sources describe faster-than-light (FTL) as violating special relativity (SR): (Reich (2011c); Cho (2011a); Choi (2011)). Other reliable sources disagree, though; for FTL not necessarily violating SR, see "Tachyon" (2011).
  3. ^ Cite error: The named reference cernrelease was invoked but never defined (see the help page).
  4. ^ OPERA (2012).