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| Speed-of-light experiments give baffling result at Cern | Speed-of-light experiments give baffling result at Cern |
| (about 3 hours later) | |
| By Jason Palmer Science and technology reporter, BBC News | By Jason Palmer Science and technology reporter, BBC News |
| Puzzling results from Cern, home of the Large Hadron Collider, have confounded physicists because subatomic particles seem to have beaten the speed of light. | Puzzling results from Cern, home of the Large Hadron Collider, have confounded physicists because subatomic particles seem to have beaten the speed of light. |
| Neutrinos sent through the ground from Cern toward the Gran Sasso laboratory 732km away in Italy seemed to show up a tiny fraction of a second early. | Neutrinos sent through the ground from Cern toward the Gran Sasso laboratory 732km away in Italy seemed to show up a tiny fraction of a second early. |
| The results - which threatens to upend a century of physics - were put online for scrutiny by other scientists. | |
| In the meantime, the group says it is being very cautious about its claims. | In the meantime, the group says it is being very cautious about its claims. |
| They will be discussing the result in detail in a conference at Cern on Friday afternoon, which can be viewed online. | They will be discussing the result in detail in a conference at Cern on Friday afternoon, which can be viewed online. |
| "We tried to find all possible explanations for this," said report author Antonio Ereditato of the Opera collaboration. | "We tried to find all possible explanations for this," said report author Antonio Ereditato of the Opera collaboration. |
| "We wanted to find a mistake - trivial mistakes, more complicated mistakes, or nasty effects - and we didn't," he told BBC News. | "We wanted to find a mistake - trivial mistakes, more complicated mistakes, or nasty effects - and we didn't," he told BBC News. |
| "When you don't find anything, then you say 'Well, now I'm forced to go out and ask the community to scrutinise this.'" | "When you don't find anything, then you say 'Well, now I'm forced to go out and ask the community to scrutinise this.'" |
| Caught speeding? | Caught speeding? |
| The speed of light is the Universe's ultimate speed limit, and much of modern physics - as laid out in part by Albert Einstein in his theory of special relativity - depends on the idea that nothing can exceed it. | The speed of light is the Universe's ultimate speed limit, and much of modern physics - as laid out in part by Albert Einstein in his theory of special relativity - depends on the idea that nothing can exceed it. |
| Thousands of experiments have been undertaken to measure it ever more precisely, and no result has ever spotted a particle breaking the limit. | Thousands of experiments have been undertaken to measure it ever more precisely, and no result has ever spotted a particle breaking the limit. |
| But Dr Ereditato and his colleagues have been carrying out an experiment for the last three years that seems to suggest neutrinos have done just that. | But Dr Ereditato and his colleagues have been carrying out an experiment for the last three years that seems to suggest neutrinos have done just that. |
| Neutrinos come in a number of types, and have recently been seen to switch spontaneously from one type to another. | Neutrinos come in a number of types, and have recently been seen to switch spontaneously from one type to another. |
| The team prepares a beam of just one type, muon neutrinos, sending them from Cern to an underground laboratory at Gran Sasso in Italy to see how many show up as a different type, tau neutrinos. | The team prepares a beam of just one type, muon neutrinos, sending them from Cern to an underground laboratory at Gran Sasso in Italy to see how many show up as a different type, tau neutrinos. |
| In the course of doing the experiments, the researchers noticed that the particles showed up 60 billionths of a second sooner than light would over the same distance. | |
| This is a tiny fractional change, but one that occurs consistently. | |
| The team measured the travel times of neutrino bunches some 15,000 times, and have reached a level of statistical significance that in scientific circles would count as a formal discovery. | The team measured the travel times of neutrino bunches some 15,000 times, and have reached a level of statistical significance that in scientific circles would count as a formal discovery. |
| But the group understands that what are known as "systematic errors" could easily make an erroneous result look like a breaking of the ultimate speed limit, and that has motivated them to publish their measurements. | But the group understands that what are known as "systematic errors" could easily make an erroneous result look like a breaking of the ultimate speed limit, and that has motivated them to publish their measurements. |
| "My dream would be that another, independent experiment finds the same thing - then I would be relieved," Dr Ereditato said. | "My dream would be that another, independent experiment finds the same thing - then I would be relieved," Dr Ereditato said. |
| But for now, he explained, "we are not claiming things, we want just to be helped by the community in understanding our crazy result - because it is crazy". | But for now, he explained, "we are not claiming things, we want just to be helped by the community in understanding our crazy result - because it is crazy". |
| "And of course the consequences can be very serious." | "And of course the consequences can be very serious." |