Neutrinos do not go faster than light, according to fresh measurements of a test last year that had suggested the particles broke the Universe's speed limit, CERN said on Friday. The new measurements were made by a team working independently from the scientists who had made the tentative but hugely controversial claim about "faster-than-light" particles.
Their findings "indicate the neutrinos do not exceed the speed of light," the European Centre for Nuclear Research (CERN) said in a press release. CERN said last month there may have been technical hitches that had skewed the initial measurements, something that critics of the findings said they had always suspected.
The controversy began last September, when CERN's so-called OPERA team cautiously announced that sub-atomic particles called neutrinos had travelled some six kilometres (nearly four ) per second faster than the velocity of light, described by Einstein as the maximum speed in the cosmos.
The neutrinos were timed at their departure from CERN's giant underground lab near Geneva and again, after travelling 732 km (454 miles) through the Earth's crust, at their arrival at the Gran Sasso Laboratory in Italy. To do the trip, the neutrinos should have taken 0.0024 seconds. Instead, the particles were recorded as hitting the detectors in Italy 0.00000006 seconds sooner than expected.
Knowing their findings would stir a storm, the OPERA team urged other physicists to carry out their own checks to corroborate or refute what had been seen. As part of this verification, an experiment called ICARUS at the Gran Sasso Laboratory took a separate look at the flight of seven neutrinos that had also been recorded by the OPERA team.
It used a new measuring technique, called a liquid argon time projection chamber. "ICARUS measures the neutrino's velocity to be no faster than the speed of light," said Carlo Rubbia, a Nobel winner and spokesperson for the ICARUS project. But he and CERN Research Director Sergio Bertolucci stoutly defended the rights of scientists to make exceptional claims and to the rights of others to verify them.
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