While the second experiment “has made an important test of consistency of its result,” Ferroni added, “a final word can only be said by analogous measurements performed elsewhere in the world.”
That is, more tests are needed, and on other experimental setups. There is still a large crowd of skeptical physicists who suspect that the original measurement done in September was an error.
Should the results stand, they would upend more than a century of modern physics.
In the first round of experiments, a massive detector buried in a mountain in Gran Sasso, Italy, recorded neutrinos generated at the CERN particle accelerator on the French-Swiss border arriving 60 nanoseconds sooner than expected. CERN is the French acronym for European Council for Nuclear Research.
A chorus of critiques from physicists soon followed. Among other possible errors, some suggested that the neutrinos generated at CERN were smeared into bunches too wide to measure precisely.
So in recent weeks, the OPERA team tightened the packets of neutrinos that CERN sent sailing toward Italy. Such tightening removed some uncertainty in the neutrinos’ speed.
The detector still saw neutrinos moving faster than light.
“One of the eventual systematic errors is now out of the way,” said Jacques Martino, director of the National Institute of Nuclear and Particle Physics in France, in a statement.
But the faster-than-light drama is far from over, Martino added. The OPERA team is discussing more cross-checks, he added, including possibly running a fiber the 454 miles between the sites.
For more than a century, the speed of light has been locked in as the universe’s ultimate speed limit. No experiment had seen anything moving faster than light, which zips along at 186,000 miles per second.
Much of modern physics — including Albert Einstein’s famous theory of relativity — is built on that ultimate speed limit.
The scientific world stopped and gaped in September when the OPERA team announced it had seen neutrinos moving just a hint faster than light.
“If it’s correct, it’s phenomenal,” said Rob Plunkett, a scientist at Fermilab, the Department of Energy physics laboratory in Illinois, in September. “We’d be looking at a whole new set of rules” for how the universe works.