It's True Light is the Speed Limit...

Einstein was right, neutrino researchers admit

KYOTO, June 9 — A team of scientists who last year suggested neutrinos could travel faster than light conceded Friday that Einstein was right and the sub-atomic particles are — like everything else — bound by the universe's speed limit.

Researchers working at the European Centre for Nuclear Research (CERN) caused a storm when they published experimental results showing the particles could out-pace light by some six kilometres per second.

The findings threatened to upend modern physics and smash a hole in Albert Einstein's 1905 theory of special relativity, which described the velocity of light as the maximum speed in the cosmos.

The neutrinos were timed on the journey from CERN's giant underground lab near Geneva to the Gran Sasso Laboratory in Italy, after travelling 732 kilometres (454 miles) through the Earth's crust. 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, the preliminary experiment had shown.

But on Friday the researchers told the International Conference on Neutrino Physics and Astrophysics, being held in Japan's ancient capital of Kyoto, that the earlier results were wrong and faulty kit was to blame.

"The previous data taken up to 2011 with the neutrino beam from CERN to Gran Sasso were revised taking into account understood instrumental effects.A coherent picture has emerged with both previous and new data pointing to a neutrino velocity consistent with the speed of light," the team said.

 The initial findings had been greeted with a combination of excitement and scepticism, even from those involved in the experiment, who 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 original team of researchers known as OPERA. Carlo Rubbia, a Nobel winner and spokesperson for the ICARUS project announced the neutrinos had kept within the universal speed limit.

In March the Italian physicist at the head of OPERA resigned following calls for his dismissal after tests contradicted the original experimental findings. "I hope OPERA will find new unity and a new leadership to pursue its main target of observing the appearance of a new type of neutrinos," said Antonio Masiero, the deputy head of the Italian Institute for Nuclear Physics. The initial findings had provoked howls of incredulity in some quarters.

"If this result at CERN is proved to be right, and particles are found to travel faster than the speed of light, then I am prepared to eat my shorts, live on TV," Jim Al-Khalili, a professor of theoretical physics at Britain's University of Surrey, declared at the time.

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