So what does OPERA find ? Their main result, based on the 15,233 neutrino interactions collected in three years of data taking, is unchanged from the September result. The most interesting part of the new publication is instead that the find that the 20 new neutrino events (where neutrino speeds are individually measured, as opposed to the combined measurement done with the three-year data published in September) confirm the earlier result: the arrival times appear to occur about 60 nanoseconds before they are expected.
It is necessary here to note that since distance from source to detector and time offsets necessary to determine the travel time of neutrinos have not been remeasured, the related systematics (estimated as well as -possibly- underestimated ones) are unchanged. The measurement therefore is only a “partial” confirmation of the earlier result: it is consistent with it, but could be just as wrong as the other.
So one type of systemic bias has been ferreted out and the results of the original experiment stand. There are still other parts of the experiment that need to be checked and prodded, but we know the initial result was not just a one-off. But there are still some potential confounds in the measurement.
Just to make an example, I will reiterate here the doubts I have on one of the time offsets necessary to obtain the timing measurement in Gran Sasso: an 8-km-long light guide brings in a 40,000+-1 ns offset: in order to determine a “delta t” of 60 nanoseconds, a subtraction of that large number has to be made. This offset was measured three years ago, and could have changed if the refraction index had changed even very slightly (e.g. due to aging of the plastic material). This offset was not remeasured in the new analysis, and the possible associated systematic uncertainty remains in my mind an issue.
One of the comments also raised an interesting point in that the neutrino generated by the meson decay may just be generated 18m away from the initial source. 60ns at the speed of light would account for an 18m “jump” quite readily. I don’t know by what mechanism the particle could jump so far, but it could be a “spooky action at a distance”, and such a jump would be easier to swallow than that the neutrinos are actually travelling faster than our already established universal speed limit. Such a tiny jump right at the outset would amount to a strange phenomenon which definitely needs much more study, but not necessarily a phenomenon that we could in theory harness to travel superluminally.
Given that we did not detect a neutrino burst any number of years prior to the supernova we detected in 1987, but rather pretty much at the same time — okay, five hours before we realized the supernova proper, but it was a pretty distant star, in another galaxy, and measuring the increase in light in it had to have been rather difficult. And if you think the five-hours-early fact explains the 60ns-early-fact of OPERA’s experiment, you might want to do a napkin calculation to sanity-check that assertion first.