The chances have risen that Einstein was wrong about a fundamental law of the universe.
Scientists at the world's biggest physics lab said Friday they have ruled out one possible error that could have distorted their startling measurements that appeared to show particles traveling faster than light.
Many physicists reacted with skepticism in September when measurements by French and Italian researchers seemed to show subatomic neutrino particles breaking what Nobel Prize-winning physicist Albert Einstein considered the ultimate speed barrier.
The European Organization for Nuclear Research said more precise testing has now confirmed the accuracy of at least one part of the experiment.
"One key test was to repeat the measurement with very short beam pulses," the Geneva-based organization, known by its French acronym CERN, said in a statement.
The test allowed scientists to check if the starting time for the neutrinos was being measured correctly before they were fired 454 miles (730 kilometers) underground from Geneva to a lab in Italy.
The results matched those from the previous test, "ruling out one potential source of systematic error," said CERN.
Still, scientists stressed that only independent measurements by labs elsewhere would allow them to declare that the results of their experiment were a genuine finding.
"A measurement so delicate and carrying a profound implication on physics requires an extraordinary level of scrutiny," said Fernando Ferroni, president of Italian Institute for Nuclear Physics. "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."
According to Einstein's 1905 special theory of relativity, nothing is meant to be able to go faster than the speed of light _ 186,282 miles per second (299,792 kilometers per second).
But the researchers said in September that their neutrinos traveled the distance from Geneva to Gran Sasso 60 nanoseconds faster, when the margin of error in their experiment allowed for just 10 nanoseconds. A nanosecond is one-billionth of a second.