Everyone who bet against Einstein better get out their wallet.
That's because those supposedly faster-than-light particles that shook up the world of physics last September are looking a lot slower.
A second experiment deep in an Italian mountain timed these subatomic particles, neutrinos, traveling at precisely the speed of light and no faster, a team from the experiment, called Icarus, said Friday.
"For us, the timing is perfectly in line with the speed of light," said Carlo Rubbia, a Nobel Prize-winning physicist and spokesman for the Icarus experiment, in a telephone interview.
The new results pile on to revelations last month that a loose cable may have compromised the original experiment, called Opera.
Although not the final word, the new results are "the greatest of hammer blows" against the faster-than-light findings, said Matt Strassler, a theoretical physicist at Rutgers University.
That's because Opera and Icarus operate in the same mountain in Italy, and both timed the same neutrinos, which were generated at the giant European Organization for Nuclear Research, or CERN, laboratory on the French-Swiss border some 450 miles north.
That makes the new Icarus results, published online, "a clear, direct refutation of the Opera measurement," Strassler said.
The Icarus results arrived during a test run of the CERN neutrinos in early November.
The Opera team also measured those neutrinos, and, like their previous result, saw them flying faster than light.
"We have two experiments with different results," Rubbia said. "We cannot be both right. One of us is wrong."
So which experiment is correct?
"I know who is right," Rubbia said. "We are right."
The Opera group said Feb. 23 that a crucial fiber-optic timing cable had a loose connection, possibly leading to an overestimate of the speed of the neutrinos.
Together, the new results and the loose cable all but restore the universe's ultimate speed limit, the speed of light, set by Albert Einstein's special theory of relativity in 1905.
Theory has held up
For more than 100 years, this speed limit, 186,282 miles per second, has held up in every test thrown at it. The speed factors into everything from estimates about the size and age of the universe to the radius of black holes to the power generated by nuclear reactors.
But in September, the large international team of Opera physicists reported seeing neutrinos arriving at their experiment from CERN about 60 nanoseconds faster than light.
Despite dissent from some team members, the Opera scientists announced their results in a scientific paper and a symposium Sept. 23. The announcement generated a wave of global publicity, but also strong skepticism from other scientists. "It'd be a very unlikely result, a very, very surprising result," Harvard physicist Lisa Randall said at the time.
"No really decent theoretical physicist took this seriously from the very start," said Nima Arkani-Hamed, a theoretical physicist at the Institute for Advanced Study in Princeton, N.J., Einstein's last academic home. " I certainly did not."
The reason: Hundreds of experiments have investigated the speed of light, and none had seen anything, even ghostly neutrinos, moving faster. And theories that propose faster-than-light particles rest on "very shaky foundations," Arkani-Hamed said.
He also criticized the Opera team for announcing their results, saying cutting-edge physics experiments often generate anomalous results that fizzle after the many sources of possible error are rechecked.
"There was no reason for them to trigger a media circus in the middle of banal twists and turns we have all the time," said Arkani-Hamed.
Final word should arrive in May, after CERN shoots more neutrinos at the Opera and Icarus detectors.
Antonio Ereditato, a member of the Opera team and the head of the Albert Einstein Center for Fundamental Physics in Bern, Switzerland, said he welcomed the latest results.
"These results are in line with our recent findings about the possible misfunctioning of some of the components of our experimental setup," he told The Associated Press on Friday.
No comments:
Post a Comment