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Home , Speed of light

Do you know why I pulled you over?

Exceeding the of has consequences, even—especially? —for . By Judith Jackson

10 Photo: Reidar Hahn | volume 9 issue 1 february 2012

11 On September 23, 2011, a press release from How fast was I going? CERN, the European Organization for Nuclear Specifically, the neutrinos from CERN arrived at Research, announced a seminar to be held that Gran Sasso one 60-billionth of a sooner very afternoon. Members of the OPERA than they should have. They crossed the finish line experiment would describe their of in Italy 20 meters ahead of light. what appeared to be a new property of neutrinos. What? We may not know much about , Observing and describing new particle prop- but there’s one thing we’re sure of, right? Nothing erties is what particle physicists do. Every year can exceed the speed of light in a . As they publish hundreds of scientific papers, each the T-shirt says: “186,000 miles per second. It’s not shedding some new light, however faint, on just a good idea, it’s the law.” the properties of the elementary particles and And yet those neutrinos, some 15,000 of them, of the world around us. Little by little, bit appeared to have done it. It looked as if they’d by bit—or so the orthodoxy goes—over the years been caught speeding. That called for a press these construct the extraordinary conference. edifice of our understanding of the fundamental In the press release and at the CERN seminar, physics of the . the OPERA collaborators presented their astonish- Some of these hundreds of papers attract ing finding with the utmost circumspection. They interest within the community. hadn’t set out to catch neutrino speeders; they’d A few cause a stir at physics conferences. A tiny been looking for oscillation from one neutrino type number come to the notice of the science-minded to another. They were as shocked as anyone when media. Hardly any get their own press conferences. they clocked neutrinos at light-defying . The OPERA result was different. They assumed they must be wrong. But after After months of checking and cross-checking months of scrutinizing their results and coming up their , their instruments, their with the same answer, they decided the time had assumptions, their math and anything else they come to ask the broader physics world to take could think of, the OPERA collaborators appeared a look. They especially invited other neutrino exper- to have observed a remarkable property of the iments, with different teams and different instru- neutrinos beaming from CERN, in Geneva, to ments, to see if their neutrinos also outpaced light. the OPERA detector in the Gran Sasso National James Gillies, CERN’s chief of communication, Laboratory in central Italy, 730 kilometers away. had learned of the result at a meeting some 10 The neutrinos appeared to be traveling faster days earlier. than light. “It was immediately obvious to me that this

12 story would be huge,” Gillies said. “I think the extremely precise measurements of the speed OPERA people knew that too. However, I think of both light and neutrinos arriving on from they felt a little overwhelmed by the response.” an exploding star known as 1987A. And well they might have, because before Given the enormous tracts of the universe they you could say “faster-than-light-neutrinos,” all hell traversed, if neutrinos were traveling at the broke loose. speeds OPERA recorded, they should have arrived on Earth a year sooner than light. In fact, “Faster than light? I’ll eat my shorts.” the neutrinos from the supernova showed up All hell broke loose in the physics community exactly when observers expected, right on time. because, if neutrinos really did travel faster than Still, despite their skepticism—one physicist light, most of would go out the volunteered to eat his boxer shorts in public window. Einstein’s 1915 theory of , if the result held up—and their cold sweat about the bedrock of 21st-century physics, has pro- taking physics back to square one, scientists found implications for everything from the work- overwhelmingly expressed respect for OPERA’s ings of your GPS to the to the work and for the scientific process. of the universe. Built into the theory of general Notwithstanding his incredulity, Wojcicki said, relativity is Einstein’s 1905 theory of special “I congratulate my [OPERA] colleagues on their relativity, which established the speed of light as meticulous work. This could turn out to be the ultimate universal speed limit. If neutrinos the most important experiment of the century.” really did break the speed limit, if E = mc² Yale neutrino physicist Bonnie Fleming agreed. turned out to be wrong, the implications for “Amid all the skepticism about the OPERA physics—and physicists—would be unimaginable. result,” she told a group of students a few days “My first reaction was shock and disbelief,” after the CERN announcement, “let’s remember Stanford physicist Stan Wojcicki, a long-time that neutrinos have surprised us before.” leader of ’s MINOS neutrino experiment, For their part, theorists wasted no time wading told a interviewer. In 2007, MINOS itself had in. Maybe, some said, neutrinos just have a differ- reported a possible sighting of neutrinos exceeding ent speed limit from other particles, as if the the speed limit, but the result was not statistically authorities set one limit for Ferraris and another for significant, and most physicists had dismissed it. everything else on the road. Maybe neutrinos Furthermore, there was sound experimental were born faster than light and just never looked evidence to put neutrinos squarely among the back. Maybe they’re …. ranks of the law abiding. Observers had reported Experimenters and theorists alike agreed symmetry | volume 9 issue 1 february 2012

Speed of light: 299,792,458 m/sec

Speed of neutrinos measured by OPERA: 299,798,454 m/sec 13 on the need for more data and on the value of Something shaking in the firmament? a scientific process that rejects no result just What is it about faster-than-light neutrinos that because it’s improbable or inconvenient. The long made them such an instant sensation in the process of independent checking and “What if?” popular media? How could Gillies so accurately theorizing began. predict that the story would be “huge”? “Okay, here is my take,” says University of Heard the one about the neutrino? Chicago astrophysicist Michael Turner. “Just saying Meanwhile, far beyond the world of physics the- Einstein was wrong gets people’s attention, ory and experiment, the story took off in popular but when how he is wrong—speed limit—is easy culture. to understand, the situation is combustible. The webcast of a garden-variety CERN seminar Add to that the fact that many people are pissed attracts an average of a couple of hundred off at the idea of a speed limit and some even viewers. When the proceedings got under way believe that the speed of light is just like the on the afternoon of September 23, some 120,000 , a barrier to break, and you have people tuned in. There aren’t that many particle a great story.” physicists in existence, even allowing for parallel Michio Kaku, a theorist at City College of New . Clearly, plenty of regular people were York, agrees. also listening. “Einstein is the cop on the block,” he told an More than 6000 neutrino news stories interviewer. “The speed of light is the ultimate appeared on September 23rd and 24th alone, speed limit in the universe. At least it was until with thousands more in following days. Still last week, when all hell broke loose with this more stories came in a mid-November second press conference.” bounce when the collaboration issued a follow-up New York Times science writer Dennis Overbye release explaining that they’d eliminated one has a similar view. potential source of error. “The speed of light is one thing people probably Discover magazine chose faster-than-light think they know about physics,” he says. “Judging neutrinos as the science news story of the year, by the coverage I saw, a lot of the attraction was even though, the editors acknowledged, it might the ‘Was Einstein Wrong?’ angle, which of course turn out not to be true. From the pages of dozens is a red herring. So people know that if this turns of publications and websites, Einstein stuck out out to be right, there is something shaking in the his tongue at readers, in the famous photograph. firmament.” Job applications to CERN climbed by 50 per- Other commentators cited the element of time cent on the day of the press conference. Who reversal—those jokes!—and, perhaps optimistically, wouldn’t want to work where they make neutrinos a fascination with physics. that break the speed limit? Science writer Geoff Brumfiel says it’s a law of At laboratories and physics departments journalism: “When the speed of light is broken, around the world, the phones lit up with pleas from there will be a story. The speed of light or a black the media for interviews with any physicist who hole.” He also believes that “fundamentally, people could spell “neutrino.” Gillies, a physicist who can do take an interest in physics.” spell neutrino in at least six languages, was in high The neutrino story had all the elements to demand by radio and TV. produce a global sensation: Einstein, the speed Headline writers loved the story. “Speed of of light, breaking the speed of light, Einstein Light Broken!” “Was Einstein Wrong?” “There Was mistaken, and . The only thing missing a Neutrino Named Bright.” “Particles Faster was a cataclysmic , although some Than the Speed of Light? Not So Fast, Some Say.” stories made an attempt to work it in. The story In the blogosphere, neutrino jokes proliferated: couldn’t miss. When experimenters finally discover the long- And the bartender says, “Sorry, we don’t serve sought , object of decades-long faster-than-light neutrinos in here.” So this neutrino searches and endless speculation, will the dis- walks into a bar. covery produce the same worldwide cultural combustion as faster-than-light neutrinos? The After neutrino announcement, Moody’s downgrades Higgs lacks Einstein’s imprimatur and as far as Einstein’s theory of general relativity to AA+. we know it moves slower than light. Still, perhaps the Higgs will break new ground and engender Neutrino. Who’s there? Knock knock. excitement that even the neutrino furor. We’ll have to wait and see. Even scientists got into the spirit. Italian After all, as one recent blog comment noted, physicist Sergio Bertolucci, CERN’s research “Someone breaks the speed limit in Italy and director, pointed out that the result could not that’s news?” be true because it breaks a fundamental law of : nothing in Italy ever arrives on time.

14 15 Photo: ReidarHahn

symmetry | volume 9 | issue 1 | february 2012