Science Puzzle
The Neutrinos That Beat Light
In 2011 a team of physicists running the OPERA experiment announced something astonishing. They had fired a beam of tiny particles called neutrinos from CERN, near Geneva, through 730 kilometres of rock to a detector in Italy, and the neutrinos seemed to arrive about 60 billionths of a second sooner than light could have made the journey. If it were true, it would break Einstein's rule that nothing travels faster than light, a rule tested and confirmed in countless experiments for more than a century.
What did the scientists do next, and what turned out to be the explanation?
The Answer
They asked everyone to help them find their mistake, and a few months later they found it: a loose cable in their timing equipment.
The team didn't announce that Einstein was wrong. They spent months checking their measurement, couldn't find a fault and then published all their results openly, explicitly inviting other physicists to look for an error. That's how science is supposed to work when a result looks too good, or too strange, to be true. With a century of evidence on one side of the scales and a single measurement on the other, the most likely explanation was always a problem with the measurement.
In early 2012 the team found two faults. The most important was a fibre-optic cable that hadn't been plugged in properly, which delayed the timing signal reaching their master clock and made the neutrinos look early. Another experiment at the same Italian laboratory, called ICARUS, measured neutrinos from the same beam and found they travelled at the speed of light, not faster.
The astronomer Carl Sagan summed up the attitude: extraordinary claims require extraordinary evidence. The OPERA team handled it well, by being open about a result they doubted themselves. No new physics came out of it; what it showed instead was science's system for catching errors working exactly as it should.
The principle: Extraordinary claims require extraordinary evidence. When one result contradicts a huge body of well-tested evidence, the first suspect is the measurement, and the right response is to check it openly and get others to test it.