by Shane L. Larson, reporting for WSNN (Write Science News Network)
If media reports are to be believed, scientific circles were turned on their heads last week when a team of scientists involved with the European Large Hadron Collider (LHC) announced they had possibly detected neutrinos travelling faster than the speed of light. If the result is true, it would challenge one of the fundamental tenets of modern physics first set down by Albert Einstein in 1905: the speed of light is the ultimate speed in the Universe.
The scientific experiment, known as OPERA, is located in the Gran Sasso underground laboratory in central Italy. A beam of sub-atomic particles, known as neutrinos, are generated at the LHC in Geneva, and directed toward Gran Sasso, 455 miles away. “Neutrinos are one of the sixteen different particles that make up all of matter and describe all the forces of nature,” explained physicist Horatio Allen Tibbets of the Cloudy Mountain National Observatory in Utah. “There are three different kinds of neutrinos, and they spontaneously change from one kind into another when they travel over long distances. That’s what the team was trying to measure.”
But during routine analysis of the experimental output, the team of scientists made an unexpected discovery. “Their data suggests that the neutrinos are arriving about 50 nanoseconds — that’s 50 billionths of a second — too soon. If they were racing a laser beam, they’d beat the laser to Gran Sasso by about 50 feet,” said Tibbets. “If it’s true, it will be an extraordinary result.” No experiment in the past 106 years has ever detected a signal travelling faster than light. “The OPERA team did exactly what they should have done,” said Tibbets. “They alerted the scientific community to their result, and now we are all digging into it.”
When asked whether or not the scientific community believes the result, Tibbets replied, “We don’t know what to believe at the moment, because there is a lot of double checking that now has to be done. The most worrisome possibility is what scientists call ‘systematic errors.’ ” When an experiment gives an anomalous result, often the cause is due to flaws or imperfections in the experiment that shift the answer away from the true result. “For example, maybe the clocks they are using to time the neutrino flight aren’t quite ticking at the same rate,” said Tibbets, “or maybe the ruler used to measure the distance to Gran Sasso was a little bit longer than we thought it was, so when it was laid end to end the distance was larger than the true distance. These are the kinds of imperfections in our technique that have to be understood before we can confidently say the neutrinos are flying faster than light.”
“Teams all over the world are trying to verify the result using their own equipment, and mathematical and computational physicists are doing calculations and simulations to try and explain what is going on,” said Tibbets.
“This is how science works, this is how science moves forward and discovers new things. We look at the world, and when faced with a conundrum or mystery, there are three possibilities: we’ve done something wrong, our previous understanding of Nature is incomplete or flawed in some way, or we’ve discovered something new.” Any of these possibilities thrills Tibbets and his colleagues. “Right now we don’t know which possibility we are facing, but one thing is true: we’re going to learn something we didn’t know before! Either about the experiment, or about Nature. We win in both cases.”
NOTE: This was, of course, the obvious thing to write about this week. I was going to write about graphene or cuperate superconductors, but I keep getting asked about this. I also must confess that I stole the “Phantom of the OPERA” bit of the title from a seminar title I saw about this topic. 🙂