THE faster-than-light neutrino saga is officially history, but the story of OPERA, the experiment behind the original claim, is not. In the same week that OPERA confirmed once and for all that neutrinos don't outpace light, it also announced its second-ever observation of a neutrino changing shape. That's exactly the phenomenon OPERA was built to capture, and it strengthens the surprising idea that ghostly neutrinos have mass.
In September 2011, OPERA claimed that neutrinos were zipping from the CERN particle physics lab near Geneva in Switzerland faster than the speed of light to its detectors in Gran Sasso, Italy. That would violate Einstein's theory of relativity. But over the following few months, two possible sources of error emerged - a leaky fibre-optic cable and a malfunctioning clock.
On 8 June at the Neutrino 2012 conference in Kyoto, Japan, the OPERA collaboration announced new measurements indicating that neutrinos travel at almost ...
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