Almost all the news on neutrinos in the mainstream press this past few months was about the OPERA experiment, and a possible violation of Einstein’s foundational theory of relativity. That the experiment turned out to be wrong didn’t surprise experts. But one of the concerns that scientists have about how this story turned out and was reported in the press is that perhaps many non-experts may get the impression that science is so full of mistakes that you can’t trust it at all. That would be a very unhappy conclusion — not just unhappy but in fact a very dangerous conclusion, at least for anyone who would like to keep their economy strong, their planet well-treated and their nation well-defended.
So it is important to balance the OPERA mini-fiasco with another hot-off-the-presses neutrino story that illustrates why, even though mistakes in individual scientific experiments are common, collective mistakes in science are rare. A discipline such as physics has intrinsic checks and balances that significantly reduce the probability of errors going unrecognized for long. In the story I’m about to relate, one can recognize how and why scientists start to come to consensus. Though quite suspicious of any individual experiment, scientists generally take a different view of a group of experiments that buttress one another.
The context of this story, though much less revolutionary than a violation of Einstein’s speed limit, still represents a milestone in our understanding of neutrinos, which has been advancing very rapidly over the past fifteen years or so. When I was a starting graduate student in the late 1980s, almost all we knew about neutrinos was that there were at least three types and that they were much lighter than electrons, and perhaps massless. Today we know much, much more about neutrinos and how they behave. And in just the last few months and weeks and days, one of the missing entries in the Encyclopedia Neutrinica appears to have been filled in.