ananyo writes "Neutrinos obey nature's speed limit, according to new results from an Italian experiment. The finding, posted to the preprint server arXiv.org, contradicts a rival claim from the OPERA experiment that neutrinos could travel faster than the speed of light. ICARUS, located just a few meters from OPERA, clocked neutrinos traveling at the speed of light, and no faster, after monitoring a beam of neutrinos sent from CERN in late October and early November of last year. The neutrinos were packed into pulses just four nanoseconds long. That meant the timing could be measured far more accurately than the original OPERA measurement, which used ten microsecond pulses. The new findings are yet another blow to OPERA's results. Researchers there had announced possible timing problems with their original measurements. For many, this will pretty much be case closed."