Last year, a team of CERN physicists observed neutrinos traveling faster than the speed of light, but now it looks as though this extraordinary measurement might be the result of a loose fiber-optic cable or a poorly calibrated atomic clock.
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In Pictures: The Large Hadron Collider
Since Einstein formulated his special theory of relativity in 1905, the speed of light has been widely regarded as the universe's ultimate speed limit. Anything moving faster than that – even the spectral neutrino, which hurtles through the universe while interacting with almost nothing, would upend the laws of physics. So quite sensibly, the physics community has turned their attention to possible sources of error.
The primary culprit is CERN's timing system. The technology is extremely complex, but the system itself is essentially composed of two synchronized clocks, one located in Geneva, Switzerland and the other in Gran Sasso, Italy, some 450 miles away. Physicists have been investigating two potential problems: a wrongly calibrated oscillator – which plays a role in synchronizing the clocks – and the fiber-optic cables that feed a GPS signal to the timing system.
That these neutrino measurements are probably the result of a bad measurement came as little surprise to most physicists.The online scientific repository arXiv.org is now replete with theoretical refutations and technical treatises on possible sources of error in these results.
One of these papers, co-authored by Boston University physicist Andrew Cohen, argued that, if the neutrinos actually had broken lightspeed, they would have rapidly lost energy, a phenomenon that was not observed in last year's experiments.
Cohen has long stressed that virtually everyone in the scientific community has, from the outset, approached these results tentatively. He said there isn't any contention in the physics community, and there really never was.
For the last month, this story has been immensely popular, despite the calm skepticism exuded by the majority of the physicists. Why exactly does this sort of Big Physics Cataclysm stimulate the public's imagination?
Let's consider what's at stake.
Literally billions of scientific measurements are predicated on the speed of light being the fastest speed there is. If the CERN results were real, all those would have to be discarded.
Many technologies depend on Einstein's theory as well, most notably, and perhaps ironically, global positioning systems, the possible source of error in the neutrino measurements.
What's more our understanding of the location of stars and other celestial bodies is largely determined by the way light waves contract or elongate when their source is moving, which everything does as the universe expands (another theory that would be upended by these results.) Valid measurements of faster-than-light neutrinos would throw a wrench in our theory how light behaves, leaving us groping in the dark when it comes to our place in the universe.
Cause-and-effect – a concept rather central to the way we think – would be undermined. Einstein's special theory of relativity states that an object traveling at the speed of light is essentially ageless – for it, time stands still. But if an object could break that threshold, then time would, theoretically, reverse direction, and the object could arrive before it departed.
These sorts of ideas are fun to consider. But the mundane reality of science is that for a seminal, well-established theory to be tossed, there has to be more than one anomalous measurement. Physicists will be the first to tell you that our theory of the universe is incomplete, but the knowledge we do have has passed an intellectual gantlet of rigorous scrutiny.
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