Neutrino particles break the cosmic speed limit

23 Sep 2011

The CERN laboratory © CERN

An international team of scientists has today announced the results of an experiment that has recorded neutrino particles travelling faster than the speed of light.

The team, which includes 200 physicists from 36 institutions in Belgium, Croatia, France, Germany, Israel, Italy, Japan, Korea, Russia, Switzerland and Turkey, said it is opening the results to broader examination because “the measurement is at odds with well-established laws of nature”.

The ‘OPERA’ experiment involved producing 15,000 neutrino beams from the CERN (European Organization for Nuclear Research) laboratory near Geneva, and detecting them 730km away at Italy’s INFN Gran Sasso underground laboratory. According to the team working on OPERA, the results “appear to indicate that the neutrinos travel at a velocity 20 parts per million above the speed of light, nature’s cosmic speed limit”.

The scientists said that, given the potential far-reaching consequences of such a result, independent measurements are needed before the effect can either be refuted or firmly established. This is why the findings have been revealed.

“The OPERA measurement is at odds with well-established laws of nature, though science frequently progresses by overthrowing the established paradigms,” said the team. “For this reason, many searches have been made for deviations from Einstein’s theory of relativity, so far not finding any such evidence.

“The strong constraints arising from these observations makes an interpretation of the OPERA measurement in terms of modification of Einstein’s theory unlikely, and give further strong reason to seek new independent measurements.”

“This result comes as a complete surprise,” said OPERA spokesperson, Antonio Ereditato of the University of Bern. “After many months of studies and cross checks we have not found any instrumental effect that could explain the result of the measurement. While OPERA researchers will continue their studies, we are also looking forward to independent measurements to fully assess the nature of this observation.” 

CERN research director Sergio Bertolucci said it was normal procedure to invite broader scrutiny when an experiment finds an apparently unbelievable result and can find no artefact of the measurement to account for it. “If this measurement is confirmed, it might change our view of physics, but we need to be sure that there are no other, more mundane, explanations,” he said. “That will require independent measurements.”

“We have established synchronisation between CERN and Gran Sasso that gives us nanosecond accuracy, and we’ve measured the distance between the two sites to 20 centimetres,” said CNRS researcher Dario Autiero. “Although our measurements have low systematic uncertainty and high statistical accuracy, and we place great confidence in our results, we’re looking forward to comparing them with those from other experiments.”

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