Oct. 7, 2011 at 9:12 PM ET
Commentators have been surprisingly fast to point to faster-than-light neutrinos as evidence that scientists could be wrong about lots of things, including the causes of climate change. But the most likely scenario is that special relativity — a theory that contends nothing can be accelerated beyond the speed of light in a vacuum — will turn out to be right. Or at least relatively right.
Two weeks after the neutrino experiments first came to light, the prevailing view among physicists is that the observations will somehow be shown to be wrong. The time measurements had to be made to an accuracy of billionths of a second. Synchronizing the time signatures over a distance of more than 450 miles of neutrino flight, from the CERN particle-physics center on the French-Swiss border to Italy's Gran Sasso National Laboratory, is extremely challenging.
Nature News cites one paper questioning whether the clock synchronizations accounted for the varying gravitational force as the neutrinos sped through the planet. General relativity's gravitational time-dilation effect might have reduced the precision of the measurements, Imperial College London's Carlo Contaldi suggested. This wouldn't be the first time that special relativity and general relativity got tangled up with each other: The satellite-based GPS navigation system has to account not only for special relativity (which would make the satellite's clocks look as if they're moving slower from the perspective of earthly clocks) but also for general relativity (which would make them seem to move faster).
Other researchers have wondered whether fluctuations in the composition of the neutrino beam are just making it seem as if some of the particles are flying faster than light, when the effect is actually being caused by those unaccounted-for fluctuations. Nobel laureate Sheldon Glashow and a colleague at Boston University, Andrew Cohen, take another tack: They say the OPERA neutrino beam doesn't bear the energy signature that it should have if the particles were exceeding the speed of light.
The leaders of the OPERA collaboration, the team that made the neutrino observations, say they've accounted for the factors that have come to light so far, including the clock-synchronization issue. But Physics World reports that up to half of the collaboration's members think it's premature to submit their findings to a scientific journal for formal publication. (So far, the results have been posted only to the ArXiv.org preprint server.)
While the OPERA physicists continue to double-check and debate their results, researchers from the U.S.-based MINOS collaboration are gearing up to do an independent neutrino-timing check. Re-analyzing the existing MINOS data is expected to take up to six months, and if new experiments are required, that could take more than a year. In the meantime, physicists will continue trying to poke holes in the OPERA observations.
Neutrinos on the air
During this week's "Virtually Speaking Science" chat, Caltech theoretical physicist Sean M. Carroll told me that OPERA's results are "almost certainly not true."
"Even the people who did the experiment will tell you that the chances are very, very small that it's right," Carroll said. "They just want people to understand that it's on the table, it's possible. They don't know what's wrong with their experiment. They would like someone else to check it, to duplicate it, to see what might be wrong."
If the observations turn out to be right, the implications would be "incredibly groundbreaking and earth-shattering," he said. But they wouldn't be beyond the power of theorists to explain, even within the framework of relativity.
"This is what we do," Carroll said. "We come up with new theories that fit crazy, unexpected pieces of data like this."
The OPERA experiment has already given rise to scores of papers on the ArXiv server, many aimed at explaining why the results aren't as crazy as they look. If the results hold up, theorists would have to adapt Albert Einstein's special relativity theory to accommodate faster-than-light observations. But Carroll says they wouldn't start from square one.
"We can say with confidence that there is some sense in which Einstein was right. He might not be the final word, but he wasn't absolutely wrong," he said. "Einstein's theories are not wrong, they've been tested right and left, and there's something right about them. They might need to be improved, they might need to be added to. ... But we're not throwing everything out and starting from scratch."
Some folks have suggested that faster-than-light neutrinos could open the way for backward time travel, reverse causality and other post-Einsteinian weirdness. In fact, folks are already collecting faster-than-light neutrino jokes. Two examples:
Carroll says that faster-than-light neutrinos would not necessarily disrupt causality and the arrow of time, and he explains why in a posting to his blog titled "Can Neutrinos Kill Their Own Grandfathers?"
"It could be true, but it doesn't have to be true. ... Theorists would have a lot of fun figuring out how the world actually works in that case," he said.
For an hourlong discussion of faster-than-light research as well as other weird frontiers of physics, including the Nobel-winning studies of our accelerating universe, listen to the full "Virtually Speaking Science" podcasts, either online or as an MP3 download. If you're a resident of the Second Life virtual world, you'll also enjoy Saturday's talk on dark energy, presented at 10 a.m. PT / SLT by the Meta Institute for Computational Astrophysics.
The climate connection
Particle physics and climate science rarely mix, but they did get mixed up this week in an opinion piece written for The Wall Street Journal by Robert Bryce, a senior fellow at the Manhattan Institute. The essay listed "five obvious truths about the climate-change issue," including this one as No. 5:
"The science is not settled, not by a long shot. Last month, scientists at CERN, the prestigious high-energy physics lab in Switzerland, reported that neutrinos might — repeat, might — travel faster than the speed of light. If serious scientists can question Einstein's theory of relativity, then there must be room for debate about the workings and complexities of the Earth's atmosphere."
That argument earned almost instant derision from the science-minded Twitterverse, spawning #WSJscience as a new hashtag. The idea that one weird experimental claim proves that other, completely unrelated scientific claims are shaky came off as laughable. The classic construction for #WSJscience tweets goes like this: "If serious scientists can question relativity, there must be room to debate [whether Earth goes around sun]." (Hat tip to @cqchoi)
Rather than engaging in an extended rant myself, let me just link to a few of the rants elsewhere on the Web, plus a few totally serious articles about the frontiers of physics.
Selected commentaries on #WSJscience:
More faster-than-light speculation: