On September 23rd, researchers from the European OPERA project made the now-famous announcement that they had observed neutrinos traveling faster than the speed of light. Given that Einstein's special theory of relativity states that nothing can travel faster than the speed of light, their proclamation was naturally met with some skepticism - various physicists stated that there was likely a flaw in the design, implementation or calculations involved the experiment. To their credit, the OPERA collaborative made a point of inviting other scientists to try to replicate their results. In the meantime, however, they've replicated those results themselves, and announced today that neutrinos still appear to be the speediest particles in the universe.
The original set of experiments consisted of generating a neutrino beam at the Geneva-based CERN particle accelerator, and shooting it 730 kilometers (454 miles) south to an underground laboratory in Gran Sasso, Italy. While photons (light particles) had been repeatedly detected at Gran Sasso 2.4 milliseconds after leaving CERN, the neutrinos reportedly made the same trip in 60 nanoseconds less time.
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In the more recent experiments, very short neutrino beam pulses were used in order to ensure precise measurements. Those pulses were just 3 nanoseconds long, separated by gaps of up to 524 nanoseconds. Twenty "clean neutrino events" were detected at Gran Sasso, which the researchers claim were precisely associated with pulses leaving CERN. In all cases, the measurements confirmed the findings that were originally presented.
As before, however, OPERA has stated that an outside party must independently verify the measurements before they can be officially confirmed.
A paper on the latest findings is available on the Inspire website.
Update May 27, 2014: Claims of faster than light neutrinos have been debunked according to this CERN press release – thanks to commenter Dan Linder for the heads-up.