Ok, thanks to a commenter (Titus) to this morning’s post, I learned of information available in the German language press that is vastly superior to anything I had seen previously— much better than today’s New York Times article, because it contains detailed and extensive quotations from a participating scientist on OPERA. [There is nothing like nearly-first-hand information.] Here is the link:
You can try Google translate and it isn’t awful, but it does contain some important mistakes; my German is good enough to read some more of it but not good enough to do a proper translation for you. I encourage someone fluent to help us out with a proper translation. Someone has done so — see the comments. [Thanks to the translator!] You’ll see, when you read it, that there are some minor discrepancies between I wrote, based on imperfect translation, and what the OPERA physicist is quoted as saying in the better translation, which is obviously what you should go with.
Facts that one can glean from this article bring me to the following conclusions:
As I suspected all along (and contrary to the original press reports), the OPERA experimenters do not claim to have found the cause of the 60 nanosecond shift in the timing of the neutrinos. They only have suspect causes. This is not the same thing. The mystery is not over yet (though it has probably entered its final chapter.)
The situation is complex, because they know of two problems, one (with an oscillator) decreasing the shift and one (with a fiber) increasing it. We now know (thanks to the German article) that both of these effects are tens of nanoseconds in size, and one (the one involving the famous faulty fiber) could be as large as 100 nanoseconds. That means that in the language of yesterday afternoon’s post, whose Figure is reproduced here, the situation with OPERA is perhaps describable as case (d), perhaps as case (e). In short, it is now confirmed that there currently is no known discrepancy — not even a weak one — with Einstein’s theory of relativity.
(a) What OPERA said originally. (b) What the original press articles on February 22nd claimed OPERA was now saying. (c),(d),(e) Three possible interpretations of OPERA's statement. In each case, a bar whose center lies at the most likely result of the measurement, and whose width indicates the degree of uncertainty, is shown. If we take OPERA's statement at face value, we still don't know if it is inconsistent with zero but less certain than before, consistent with zero, or simply unknown (in which case the previous measurement must be discarded.) We now know what was implied was something like (d) or (e).
Despite all of the jokes and snide remarks, it sounds as though the problem with the fiber was quite difficult to find, and was a really nasty one: it depended very sensitively on exactly how the fiber was screwed in, which means a defective fiber or a defective connection, I guess. We’re not just talking about an ordinary loose wire. This is not inconsistent with what my experimental colleagues tell me about looking for sources of electronics problems; in particular, note the comment (highlighted in red) from this morning’s post.
The experimenters believe that over the coming weeks they can, with some considerable effort, nail down to some degree how big these two effects were. If they succeed, perhaps they will be able to bring case (d)/(e), which is what we are currently dealing with, back closer to case (a) or (b), or at least case (c). We’ll see what they say then. But no one, not even OPERA, will be very confident in the result at that point.
OPERA cannot be absolutely sure that they have found the cause of the timing shift in the neutrinos — and that there are no other major problems — until they rerun the experiment, to see whether fixing the two problems changes last year’s result by just about 60 nanoseconds. Apparently this is not something they can tell post facto just by looking at the way the fiber and the oscillator behave now; it is still not entirely clear why, but surely the devil here is in the details, and we won’t get those from press articles.
Apparently there are people within OPERA who argued back in September that the result was not ready for public presentation. They are vindicated now.
Several experiments (OPERA, ICARUS, BOREXINO, and apparently another one I didn’t know about, LVD) will all attempt the neutrino speed measurement, independently but simultaneously, this spring. (The neutrino beam is very wide when it arrives at the Gran Sasso laboratory, and all of the experiments sit inside it.) Hopefully OPERA will have eliminated its problems, and the other three experiments will not make any mistakes, and all four experiments will get the same answer. Of course these are very hard measurements, so they might not get the same answer. We’ll see. If they all find no shift, then we’re all happy with Einstein and the story is over. If only OPERA finds a shift, and it is still 60 nanoseconds (or comparable), then we’ll know the OPERA folks still haven’t found the source of their problem. If all the experiments find the same non-zero shift, we’ll start talking about Einstein and relativity again… but don’t hold your breath.
