I wanted to make a few assorted comments about the OPERA experiment’s painful climb-down, and about yesterday’s widespread response to it, which bothered me a lot. You may want to read my initial post from yesterday, and also my attempt to sharpen the main question OPERA left unanswered in my second post. [ALSO: look ahead to the next post, in which many of the confusions that were still present at the time of this post were resolved.]
Over the past day I’ve learned enough to be
pretty convinced (but not certain) that the situation that we are in is case (e) [or a version of case (d)] as described in yesterday’s post: that probably the previous OPERA experimental data is tainted and we can draw no conclusions from it at all. It’s not that they found a problem that shifts their data so that it is consistent with Einstein’s relativity [case (b) from yesterday], and they can say that the neutrinos travel as expected. (Press reports that said so are just wrong.) It’s that they found a problem that means their data from last year can’t be interpreted at all… at least, not at the moment, and maybe not ever. If true, this would indeed mean that there is no longer any data from OPERA that can be used to measure neutrino speeds to good accuracy, and we’re back where we were before OPERA ran in the first place: with no reason to think there’s anything amiss with Einstein’s relativity equations. As for OPERA, the only way forward is to rerun the experiment (apparently in March-April-May.)
[The NY Times article that appeared today (which attributes OPERA, a non-CERN experiment, to CERN; what has journalism come to these days?) has some additional details, but if you read it carefully, those details don't change anything written in this post. See the first comment at the very end of this post.]
Ok, some comments.
First: I think it is important for people to understand that the last couple of days have been pretty ordinary days in the particle physics world. Most physicists I know said “oh,” when they heard the news that problems had been identified at OPERA, spent a few minutes chatting about it, and went back to work. One of my famous senior colleagues, whom I was emailing for an unrelated reason, ended his email this way: “Thanks! I hope that things are going well for you. And, apparently, one less neutrino puzzle to worry about ….” (The ellipsis was his.)
Why so blasé? Almost all of my colleagues had put very, very low odds on the OPERA experiment’s result being correct — not because the people who did the measurement were considered incompetent or stupid, but because (a) doing experimental physics is very challenging; (b) this particular result was especially implausible; and (as everyone in the field knows) (c) most experiments with a shocking result turn out to be wrong, though it can take months or years to find the mistake.
The press (and therefore the public) never really quite understands how rare it is for claims of extraordinary discoveries to stand the test of time. And that’s why although the press makes such a big deal out of a first announcement of an exciting result, in the scientific community it is often only the second, or even third, confirming experiment (sometimes done by the same people, sometimes by others) which turns a raised eyebrow into a raised level of interest.
Second: I am astonished and dismayed at the level of vitriol and scorn heaped publicly on the OPERA folks for having… for having … for having done what?
We know there is a problem with a wire. But I don’t know yet what it is, or why they failed to find it. I certainly don’t know why it would make the neutrinos appear to arrive early in the same way in both OPERA-1 and OPERA-2; a random problem wouldn’t obviously do that. I don’t know if they simply overlooked the problem, or if it was particularly difficult to find for some reason. “Faulty wire” makes for good headlines, but do you know what it means? I don’t.
Anyone who has tried to find an intermittent problem in an electrical circuit knows it can be maddeningly difficult. Read this comment I received yesterday, from someone who obviously has a lot more experience than I have:
“One thing people outside the field may not realize is that in even in a relatively simple particle physics experiment, the data acquisition system can easily use hundreds or thousands of cables (electrical and fiber optic), of many different lengths running from many different locations to many other different locations. A bad cable, or a bad connector, or a mislocated cable can be the cause of endless grief; sometimes it causes an obvious problem that clearly points back to the cable or connection in question, but sometimes it can just cause subtle timing effects that are monstrously difficult to diagnose. Even if a bad cable or connection is found it’s not always clear what effect it might have had on previously collected data, and it may not be possible to correct the data to account for it (other than by blowing up the systematic error to the point where any result is more or less meaningless.) I see no CYA conspiracy here, just scientists doing their job carefully after finding the sort of problems you try hard to avoid in the first place but which happen to the best of us at times.”
Usually (not always) when an experiment fails, it does so because something went awry that wasn’t obvious for some reason. Let’s wait to find out what the case was this time, before insulting people.
Third: Many people in the particle physics community feel (and felt from the beginning) that OPERA should have been more patient and done far more checks of the result before they released it. Generally, I’m one of them, but a problem for OPERA was that their result had to do with Einstein, and anything having to do with Einstein gets blown up into the biggest-thing-ever by both press and public. Einstein’s an icon of our modern age, like Newton to the previous one; anything that could unseat his equations and concepts, even in a small way, is big news. And of course if OPERA were correct, it would actually be huge news. So I don’t know if OPERA could have avoided the situation that they got themselves into. [CERN, which isn't even the host lab for OPERA and has no affiliation or membership in it, is another matter; why they got themselves involved I have no idea.] In addition, OPERA’s result was announced to the world not by OPERA itself, but in a leak by a blogger; so the situation got away from them even at the start. I doubt they could have kept it secret for the months it took to find the wire problem. They would have had to work very hard to downplay the result; I wish they had made a great effort to do that, but I don’t know if it would have helped in the end.
Finally, I would like to remind you what it means to be a scientist, and human. Let me quote something that I said in my very first post after the OPERA paper appeared (you may enjoy reading the whole post, to see how it looks in hindsight). I wrote:
A last remark for the night: think about what it is like to be an experimentalist making a revolutionary statement of this magnitude. Talk about sticking your neck out! This result either means a Nobel Prize or international embarrassment — perhaps even ridicule if a serious mistake was made; there’s no middle ground. The combination of excitement, hope, and terror must be unlike anything most of us will ever experience. I cannot imagine how any of them have slept for days; I cannot imagine that they will sleep well for months, until a second experiment reports, “We have measured the speed of neutrinos, and we confirm…”
They’re suffering plenty. No one needs to make it any worse by being cruel, especially before we know the whole story.