The hunt for the “OPERA error” now seems all but over. The solution to the (Duhemian) problem of where to lay the “blame” for the anomalous speed of light result appears to be at hand, after some months of sleuthing. Note how the same, remodeled, and new data are used both to identify and warrant inferences to rule out and (finally) identify sources. Searching does not penalize in such identifications of known effects. Had they inferred the experimental malfunction(s) Ai earlier (faulty fiber-optic cables), would you accord it greater, lesser, or identical weight? Why?*
By Brian Vastag, Friday, March 16, 1:50 PM
Anyone 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 now looking a lot slower.
A second experiment deep in an Italian mountain timed these subatomic particles, called neutrinos, traveling at precisely the speed of light and no faster, a team from the experiment, called ICARUS, announced 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 both OPERA and ICARUS operate in the same mountain in Italy, and both timed the same neutrinos, which were generated at the giant CERN laboratory on the French-Swiss border some 450 miles north.
That makes the new ICARUS results, which were published online Thursday, “a clear, direct refutation of the OPERA measurement,” said Strassler.
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,” said Rubbia. “We cannot be both right. One of us is wrong.”
So which experiment is correct?
“I know who is right,” Rubbia said, chuckling. “We are right.”
On Feb. 23, the OPERA group said 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.
For over a century, this speed limit — 186,282 miles per second — has held up in every test thrown at it.
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 noted 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 probed the speed of light, and none had seen anything — even ghostly neutrinos — moving faster. And wild 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 that cutting-edge physics experiments often generate anomalous results that fizzle after the many sources of possible error are re-checked.
“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.
Asked whether he was disappointed that the prospect of breaking light speed probably remains in the realm of science fiction, Ereditato told the AP: “This is the way science goes. What matters is the global progress of scientific knowledge.”
*Note that they did not start out with a conjunction of auxiliaries to derive the predicted experimental result (with Ai one of many)—though some philosophers may wish to reconstruct it that way.