The team which found that neutrinos may travel faster than light has carried out an improved version of their experiment - and confirmed the result. If confirmed by other experiments, the find could undermine one of the basic principles of modern physics.
Nothing's changed about the neutrinos, of course. But the Italian Institute for Nuclear Physics (INFN) researchers who shocked the world in September with a claim that they'd measured particles traveling faster than the speed of light now say a potential flaw in their experiment has been ruled out.
"New tests conducted at the Gran Sasso National Laboratory of INFN by the OPERA Collaboration, with a specially set up neutrino beam from CERN, confirm so far the previous results on the measurement of the neutrino velocity," the INFN team said in a statement released Friday. "The new tests seem to exclude part of potential systematic effects that could have affected the original measurement."
In September, an international team of scientists led by Dr. Sergio Bertolucci reported that particles they had been firing for several years from the CERN particle accelerator in Switzerland at detectors at the OPERA facility in Gran Sasso, Italy located about 450 miles away appeared to be arriving at their destination a fraction of a second earlier than the time it would take light to get there.
The particles, traveling through air, water, and rock, shouldn't have hit the Gran Sasso detectors any sooner than about 2.4 thousandths of a second after being fired, which is the time it would take light to travel the distance between the two points. Yet the CERN researchers reported that their neutrinos were getting to the target 64 nanoseconds faster—meaning that they were traveling faster than light, supposedly impossible according to Albert Einstein's Special Theory of Relativity.
That news sent the scientific community into an uproar, spawned breathless headlines questioning whether E still equaled MC squared, and gave new hope to anyone who has dreamt of faster-than-light travel to distant stars and planets.
The report also kick-started a movement to show that the results were somehow flawed—in short, science started doing what it's supposed to do when surprising and potentially groundbreaking results are published.
Among the possible flaws in the OPERA team's experiment pointed out by other scientists was the absence of energy loss by the neutrinos, which a pair of Boston University physicists argued would be detectable if the particles had traveled faster than light. Other scientists questioned whether the team had correctly accounted for the effects of relativity on the GPS satellites they used to measure the amount of time it took for the neutrinos to travel from point A to point B in their experiment.
The INFN team set out to re-run the neutrino experiment late last month. While results are not yet conclusive, the team says it's now ruled out a possible error in the measurement of the starting time for the neutrinos as they were fired from an accelerator in Geneva to the OPERA facility in Switzerland.
"A measurement so delicate and carrying a profound implication on physics requires an extraordinary level of scrutiny," said INFN president Fernando Ferroni. "The experiment OPERA, thanks to a specially adapted CERN beam, has made an important test of consistency of its result. 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."
Jacques Martino, director of the National Institute of Nuclear and Particle Physics of French CNRS, added that the team was re-checking other potential flaws in the original experiment.
"One of the eventual systematic errors is now out of the way, but the search is not over," Martino said. "There are more checks of systematics currently under discussion, one of them could be a synchronization of the time reference at CERN and Gran Sasso independently from the GPS.
