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Faster-than-light neutrinos expose the inner workings of science

The views expressed are those of the author and are not necessarily those of Scientific American.


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"Do you think the missing 60ns got lost down there?" Credit: ICARUS

It looks like the faster-than-light neutrino saga – or should that now be slower-than-light or the-same-speed-as-light? – may nearly be over. On Friday, CERN updated their statement on the initial OPERA result with some new results from ICARUS, another experiment at the Gran Sasso laboratory in Italy.

Here are the important bits of the statement:

The ICARUS measurement, using last year’s short pulsed beam from CERN, indicates that the neutrinos do not exceed the speed of light on their journey between the two laboratories.
[...]
The ICARUS experiment has independent timing from OPERA and measured seven neutrinos in the beam from CERN last year. These all arrived in a time consistent with the speed of light.

The ICARUS experiment has also uploaded a paper to arXiv.org, if you want more detail on how they conducted the experiment. (Or if you like your sentences oddly worded, like this: “The result is compatible with the simultaneous arrival of all events with equal speed, the one of light.”)

So, that’s that. Or is it?

In the updated statement, CERN Research Director Sergio Bertolucci stresses the importance of rigour in scientific experiments. Bertolucci says:

The Gran Sasso experiments, BOREXINO, ICARUS, LVD and OPERA will be making new measurements with pulsed beams from CERN in May to give us the final verdict. In addition, cross-checks are underway at Gran Sasso to compare the timings of cosmic ray particles between the two experiments, OPERA and LVD.

The more measurements we have, the more sure we can be of the result. But the evidence is starting to suggest that the initial OPERA result was wrong.

Bertolucci goes on to say:

Whatever the result, the OPERA experiment has behaved with perfect scientific integrity in opening their measurement to broad scrutiny, and inviting independent measurements. This is how science works.

[Emphasis mine.]

A commenter on this blog has said that the whole faster-than-light neutrino saga (as I’m quite enjoying calling it) is a “failure of communication rather than physics.” But I don’t think it is necessarily a failure of anything.

As many people have pointed out, OPERA behaved exactly as they should have done. There was no way they could have sat on the result until they had checked it further. It would have leaked eventually, and them keeping quiet wouldn’t have helped speculation or science. More, independent measurements are always good. Openness, in theory, is always good.

When they announced their result, they did so in the best possible way. In a statement the collaboration said:

Given the potential far-reaching consequences of such a result, independent measurements are needed before the effect can either be refuted or firmly established.

Once the result was announced, there was no way the media could have not reported on it. If it was true, it would have changed physics forever.The general tone of articles about the initial result suggested that most news outlets were sceptical of the result. In a good way. It was more “Oh look, some physicists might have proved Einstein wrong, weird huh?” than “OH MY GOD RUN FOR THE HILLS CAUSALITY IS NO MORE!”.

Ok, the whole “dodgy wiring” update was too good not to poke a little fun at. But it was harmless. I don’t think anyone who commented on it sounding a little silly was suggesting that the scientists had been stupid to make that mistake. I certainly was not suggesting that.

In a way, to put the result down to an experimental error as mundane as dodgy wiring is rather comforting. It reminds us that science is done by scientists who are human too, and fallible just like everyone else. (Except their mistakes almost accidentally bring down Einstein’s theory of relativity, rather than resulting in a broken hairdryer.)

In fact I’m inclined to think that the faster-than-light neutrino saga has been rather good for the relationship between science and the rest of us. Or, at least, it has the potential to be good. Perhaps now we can stop pretending that science is this big impersonal entity that moves along in increments the exact size of a scientific paper. Perhaps we can realise that science and scientists can make mistakes, but that’s ok.

If the story of the faster-than-light neutrinos is a failure of anything, it’s the way we think about science. Sergio Bertolucci was right when he said “this is how science works.” We just need to get used to it.

Kelly Oakes About the Author: Kelly Oakes has a master's in science communication and a physics degree, both from Imperial College London. Now she spends her days writing about science. Follow on Twitter @kahoakes.

The views expressed are those of the author and are not necessarily those of Scientific American.





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  1. 1. S. Dinowitz 1:49 pm 03/19/2012

    It certainly looks like case closed on FTL neutrinos – however OPERA and other labs that have committed to a retest before summer should still do so. Also, I find no mention of the energies of the 7 detected neutrinos in the latest ICARUS paper. Considering that the first part of the paper mentions the energy range of several past experiments and given the level of detail in TABLE 1 for each of the 7 events, the fact that the energy of the detected neutrinos is absent is a little suprising and annoying. However, until I find out otherwise I assume ICARUS, like OPERA, detected muon-neutrinos in the 20 to 40 GeV range. If however this is not the case, and those 7 neutrino events are less than 20 GeV then those ICARUS vs OPERA charts may be telling us something very different than ICARUS – right and OPERA – wrong.

    Link to this
  2. 2. Catamount 3:05 pm 03/19/2012

    @S. Dinowitz

    You do make a good point, and it is something that should be been included in the paper, though I certainly suspect that the physicists are aware of the potential significance of the energy levels of the neutrinos. If not, OPERA would certainly bring it up, but I think everyone involved would know to avoid such an obvious error as introducing a new variable like that (differing energy levels from the original).

    Still, it IS annoying that it wasn’t included.

    Link to this
  3. 3. jtdwyer 8:43 pm 03/19/2012

    The reason statements of these results are “oddly worded” (highly qualified), i.e., “The result is compatible with the simultaneous arrival of all events with equal speed, the one of light” is that the “time of flight” of light over the distance actually traversed by detected neutrinos cannot be determined.

    Firstly, while the ICARUS procedure reestimated the distance between the two sites, (now though to be more precise), the actual traversal path taken by detected neutrinos is indeterminable – some relativistic and/or gravitaitonal effects imparted to the non-zero rest mass neutrinos may not have been adequately considered. Secondly, light cannot traverse a direct path between the two sites because it would have to penetrate solid rock. Lastly, the neutrino “time of flight” is compared to a simple estimate of the speed of light in a vacuum over the presumed propagation distance.

    As a result or these issues, the neutrino traversal times cannot be definitively compared to the actual speed of light. As I’ve previously suggested, a lunar based neutrino detector should allow more definitive determinations of actual neutrino speed, more directly compared to the actual speed of light in a relative vacuum.

    Link to this
  4. 4. Kelly Oakes in reply to Kelly Oakes 6:33 am 03/21/2012

    jtdwyer,

    “oddly worded” did not mean “highly qualified”. I know why these statements must be qualified. I still think that sentence is a bit oddly worded. But I’m not saying it should be otherwise, it just amuses me sometimes. (I spent a large portion of the masters year of my degree reading particle physics papers and I had to get my kicks somewhere…)

    Link to this
  5. 5. Postman1 9:41 pm 03/25/2012

    So, it seems that this matter is settled, at least for the time being. I think the most important part of this entire production is the line from above:
    “Bertolucci goes on to say:

    Whatever the result, the OPERA experiment has behaved with perfect scientific integrity in opening their measurement to broad scrutiny, and inviting independent measurements. This is how science works.”

    The same holds true for ALL branches of science. Those who fail to follow this rule are not engaged in science, but rather, religion.

    Link to this

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