The ICARUS detector in Gran Sasso, Italy, also part of CERN, measured neutrinos and found they travel at sub-light speed.

Last September the whole scientific community was set ablaze by a the controversial claim set forth by CERN scientists, part of the OPERA experiment, in which they announced that they had measured neutrinos traveling at a velocity faster than the speed of light – 60 nanoseconds faster to be more exact. The implications of this statement are monumental. One of the cornerstones of physics is that nothing can travel faster than the speed of light, an axiom postulated by Einstein, which had it been proven wrong would have forced scientists to re-think physics all together.

A new set of measurements carried out by a different group of CERN scientists, from the rival ICARUS experiment, did not reach the same conclusions, as their findings  “indicate the neutrinos do not exceed the speed of light,” as stated in the official CERN press release. The Universe’s speed limit is still in place.

Although the OPERA scientists cautiously announced their results last year, after measurements that lasted well over a year, their paper was one of the most scrutinized works in recent scientific history – they knew this from the very get go, and moreover urged for independent measurements that could confirm or refute their findings. Since then, scientists all over the world, conservative and eccentric alike, have been trying to find and propose various flaws in the OPERA experiment.

Located just a few metres from OPERA, the ICARUS experiment at the Gran Sasso Laboratory took a separate look at the flight of seven neutrinos that had also been recorded by the OPERA team. These were studied using a new measuring technique, called a liquid argon time projection chamber. The ICARUS scientists thus studied that beam of neutrinos packed into pulses just four nanoseconds long, instead of the ten microsecond long pulses used by the OPERA experiment. This allowed for a more accurate measurement of the timing. They eventually concluded that neutrinos traveled slightly below the speed of light.

“Our results are in agreement with what Einstein would like to have,” says Carlo Rubbia, the spokesperson for ICARUS and a Nobel-prize winning physicist at CERN.

The OPERA team itself announced sometime last month that they had uncovered possible timing problems with their original measurements, fact confirmed by ICARUS. “The OPERA case is now conclusively closed,” says Adam Falkowski, a theoretical physicist at the University of Paris-South in Orsay, France.

What’s important to note, though is that the CERN scientists at OPERA shouldn’t be blamed for their faulty paper, but actually praised for their hard work, perseverance and even courage for stepping up and assuming responsibility. Research Director Sergio Bertolucci stoutly defended the rights of scientists to make exceptional claims and to the rights of others to verify them.

“Whatever the result, the OPERA experiment has behaved with perfect scientific integrity in opening their measurement to broad scrutiny and inviting independent measurements. This is how science works,” said Bertolucci.

source – Nature