The mind-boggling recording of particles that travelled faster than Einstein deemed possible may have been caused by dodgy wiring, scientists at one of the world's largest laboratories have revealed.
Researchers at the Cern physics lab near Geneva startled the science world in September by observing subatomic particles that seemed to be moving faster than the speed of light under the mountains of Switzerland and Italy.
They have now announced that problems with the lab's GPS time stamp and a cable might have produced the incredible result.
"If confirmed, one [defect] would increase the size of the measured effect, the other would diminish it," said a Cern statement.
University of Auckland physicist David Krofcheck, who has worked on the Large Hadron Collider, said the result was not surprising.
"You don't make a living betting against Albert Einstein, so you've got to be incredibly careful. This is just what happens when you work with modern high technology.
"In a giant experiment with hundreds of people looking, there's always a little cable, a little wire that if you just touch it or jiggle it, it can throw off your signal. And it is very subtle."
He pointed out that one of the defects might have understated the flight speed of the ghostly particles. That meant the particles might have actually travelled even faster than in the original recording.
In the original experiments, scientists fired minuscule particles called "neutrinos" under the ground between Swiss and Italian labs 720km apart. The neutrinos appeared to arrive sixty billionths of a second faster than the speed of light (299,792km/second).
This finding posed numerous unsettling possibilities, not least the scenario in which information could be sent back in time. If a signal could travel faster than the speed of light, it would be received before it was sent.
Dr Krofcheck said: "It's still tantalising and I still hope in my heart of hearts that it's true that neutrinos can go faster than light. But that's just a wish. I'm counting on Einstein coming through in the end."
Researchers will attempt to fix the hardware and resume their tests, with another result expected in May.
University of Surrey physicist Jim Al-Khalili, who famously promised to eat his boxer shorts on live television if neutrinos were shown to travel faster than light, praised the researchers' methods.
"The ... scientists are showing great integrity in announcing these potential faults in their measurements, so let's wait and see," he said. "But I suspect, now more than ever, that both Einstein's theory and my boxer shorts are safe."
September 2011: Scientists fire beams of tiny particles ("neutrinos") a distance of 720km under the ground from Geneva, Switzerland, to Gran Sasso, Italy.
* The speed at which the neutrinos reach the end point is recorded as 60 billionths of a second faster than the speed of light. The trip would take a light beam 2.4 milliseconds to complete.
* It appears to contradict Einstein's theory of special relativity (E=mc2), which states that nothing can travel faster than the speed of light.
November 2011: The scientists measure the beams with greater accuracy and make the same startling finding.
February 2012: Two possible defects are found. A faulty optical fibre connection may have led to an exaggeration of the neutrinos' speed, while a GPS problem may have understated the speed of the particles.