The OPERA neutrino detector in Italy, which received neutrino beam from CERN laboratory in the Alps. Alberto Pizzoli/AFP/Getty Images

In fairness, even the scientists who performed the experiment had their doubts. When they reported in September that they had measured subatomic neutrinos traveling faster than light, they used the word " anomaly."

The anomaly, they now concede, may have been in their own equipment - perhaps a bad connection between a GPS unit and a computer when they shot beams of neutrinos from the CERN laboratory in the Swiss Alps to a detector 450 miles away near Gran Sasso, Italy. Last year's experiment, done with a giant apparatus called OPERA, showed the neutrinos making the trip 60 nanoseconds faster than a light beam would.

That would have been a major challenge to Einstein's theory of relativity, which said light, moving at 186,000 miles per second, was at a sort of cosmic speed limit. Einstein's work has proved remarkably durable over the years, which was why the neutrino experiment had the physics world talking.

"The feeling that most people have is this can't be right, this can't be real," James Gillies, a spokesman for CERN, said back on Sept. 23.

Precisely.

Today, in a statement, CERN said the scientists were concerned about "the optical fibre connector that brings the external GPS signal to the OPERA master clock, which may not have been functioning correctly when the measurements were taken. If this is the case, it could have led to an underestimate of the time of flight of the neutrinos."

New experiments, CERN said, are now scheduled for May.

The neutrino was only proposed in 1930 as a mathematical construct to explain the behavior of other subatomic particles. Scientists say vast numbers of them (probably traveling at the speed of light) harmlessly pass through matter - including your body - all the time. Vast detectors, usually giant containers of pure water deep in underground mines, were set up to try to detect neutrinos. They were finally spotted in 1956. Not until the last decade was anyone even able to demonstrate that they have mass.

Scientists will tell you experiments need revision all the time; you publish research papers as an invitation to other scientists to validate - or disprove - your findings. Rarely, though, is such a high-profile experiment called into doubt by what, as the journal Science suggests, may have been little more than a loose cable.

So did neutrinos actually undo Einstein's relativity theory? Not so fast.