Scientists who last month appeared to have found that certain subatomic particles can travel faster than light have fine-tuned their experiment to check whether the remarkable discovery is correct.

Modified experiments — the result of suggestions from other physicists about potential flaws in their research — should be completed before the end of the year. The original experiment involved firing beams of neutrinos through the ground from the CERN facility near Geneva to the Gran Sasso laboratory in Italy 720km away. The neutrinos seemed to arrive 60 billionths of a second earlier than if they had been travelling at light speed in a vacuum. The finding appeared to conflict with Albert Einstein's theory of special relativity. If correct, this opens up the troubling possibility of being able to send information back in time, blurring the line between past and present and wreaking havoc with the fundamental principle of cause and effect.

Jim Al-Khalili, professor of physics at the University of Surrey and a broadcaster, expressed the incredulity of many in the field: “If the CERN experiment proves to be correct and neutrinos have broken the speed of light, I will eat my boxer shorts on live TV.” First time around, the CERN scientists fired pulses of neutrinos lasting about 10 microseconds each through the rock to Gran Sasso. In the new tests, the beams will be thousands of times shorter — about one or two nanoseconds — with large gaps between them. This will allow scientists to time the arrival of the neutrinos at Gran Sasso with greater accuracy and, hopefully, offer more information on the anomalous faster-than-light results.

Since the Opera (Oscillation Project with Emulsion-tRacking Apparatus) team announced their results, physicists around the world have published scores of online papers trying to explain the finding as either the result of a trivial mistake or evidence for new physics.

Dr. Carlo Contaldi of Imperial College London, for example, suggested different gravitational effects at CERN and Gran Sasso could have affected the clocks used to measure the neutrinos. Others have come up with ideas about new physics that modify special relativity by taking the unexpected effects of higher dimensions into account. — © Guardian Newspapers Limited, 2011

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