Neutrinos are still faster than light, second test reveals

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A new test appears to provide further evidence that neutrinos can indeed travel faster than the speed of light.

The latest experiment was carried out to check the findings of a test taken in September which was met which much scepticism by the scientific community. Previously, 15,000 neutrino beams were fired from CERN in Switzerland to the Gran Sasso laboratory, an underground Italian laboratory near Rome, 720km away. Physicists on the OPERA experiment said that despite checking and rechecking results, they believed that the neutrinos had travelled at a velocity 20 parts per million faster than the speed of light – a theory that challenged the law of physics and put into question Einstein's theory of relativity. Once again, the latest experiment took place at the Gran Sasso laboratory using a neutrino beam from CERN. However, this time the test aimed to exclude one potential systematic effect that may have affected the original measurement. One potential source of error in the first results was that the pulses of neutrinos sent by CERN were relatively long at around 10 microseconds each, so measuring their exact arrival time at Gran Sasso could have had relatively large errors. To account for this, the beams sent by CERN in this latest experiment were around three nanoseconds shorter, with large gaps of 524 nanoseconds between them, meaning the scientists at Gran Sasso would time their arrival more accurately. Fernando Ferroni, president of the Italian Institute for Nuclear Physics (INFN), said: "A measurement so delicate and carrying a profound implication on physics requires an extraordinary level of scrutiny. The positive outcome of the test makes us more confident in the result, although a final word can only be said by analogous measurements performed elsewhere in the world. Compared to the previous measurement, the neutrinos bunches are narrower and more spaced from each other. This permits to make a more accurate measure of their velocity at the price of a much lower beam intensity." Jacques Martino, director of the French National Institute of Nuclear and Particle Physics, who worked on the second experiment said that while this test was not a full confirmation, it did remove some of the potential systematic errors that may have occurred in the first one. "The search is not over," he said in a statement. "There are more checks of systematics currently under discussion." If the findings are correct, it would result in a complete rethink of how the cosmos works and, ultimately, could pave the way for the potential of time travel.