Speed-of-light results under scrutiny at Cern

Opera detector Enormous underground detectors are needed to catch neutrinos, that are so elusive as to be dubbed "ghost particles"

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A meeting at Cern, the world's largest physics lab, has addressed results that suggest subatomic particles have gone faster than the speed of light.

The team has published its work so other scientists can determine if the approach contains any mistakes.

If it does not, one of the pillars of modern science may come tumbling down.

Antonio Ereditato added "words of caution" to his Cern presentation because of the "potentially great impact on physics" of the result.

The speed of light is widely held to be the Universe's ultimate speed limit, and much of modern physics - as laid out in part by Albert Einstein in his theory of special relativity - depends on the idea that nothing can exceed it.

Start Quote

We want to be helped by the community in understanding our crazy result - because it is crazy”

End Quote Antonio Ereditato Opera collaboration

Thousands of experiments have been undertaken to measure it ever more precisely, and no result has ever spotted a particle breaking the limit.

"We tried to find all possible explanations for this," the report's author Antonio Ereditato of the Opera collaboration told BBC News on Thursday evening.

"We wanted to find a mistake - trivial mistakes, more complicated mistakes, or nasty effects - and we didn't.

"When you don't find anything, then you say 'well, now I'm forced to go out and ask the community to scrutinise this'."

Friday's meeting was designed to begin this process, with hopes that other scientists will find inconsistencies in the measurements and, hopefully, repeat the experiment elsewhere.

"Despite the large [statistical] significance of this measurement that you have seen and the stability of the analysis, since it has a potentially great impact on physics, this motivates the continuation of our studies in order to find still-unknown systematic effects," Dr Ereditato told the meeting.

"We look forward to independent measurement from other experiments."

Graphic of the Opera experiment

Neutrinos come in a number of types, and have recently been seen to switch spontaneously from one type to another.

The Cern team prepares a beam of just one type, muon neutrinos, and sends them through the Earth to an underground laboratory at Gran Sasso in Italy to see how many show up as a different type, tau neutrinos.

In the course of doing the experiments, the researchers noticed that the particles showed up 60 billionths of a second earlier than they would have done if they had travelled at the speed of light.

This is a tiny fractional change - just 20 parts in a million - but one that occurs consistently.

The team measured the travel times of neutrino bunches some 16,000 times, and have reached a level of statistical significance that in scientific circles would count as a formal discovery.

But the group understands that what are known as "systematic errors" could easily make an erroneous result look like a breaking of the ultimate speed limit.

That has motivated them to publish their measurements.

"My dream would be that another, independent experiment finds the same thing - then I would be relieved," Dr Ereditato told BBC News.

But for now, he explained, "we are not claiming things, we want just to be helped by the community in understanding our crazy result - because it is crazy".


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  • rate this

    Comment number 165.

    Systematic error in this sort of experiment is going to be a whole lot more subtle than something like neglecting the motion of the earth. It's bafflingly popular to believe professional scientists are likely to have forgotten to include trivial effects that an untrained person could come up with off the top of his or her head. Singular lack of respect for a highly-trained profession.

  • rate this

    Comment number 164.

    How can people insult CERN or say results shouldn't be published until peer reviewed. The purpose of the Internet is to publish CERN's physics results. Kindly they allow others to use the network. Some people need to remember whose house they are in.

  • rate this

    Comment number 163.

    @rideforever - er they have not been disproved - hence all the brouhaha. The point of this whole issue is that it would disprove the theories.

    Incidentally what else do you think has disproved them.

    Please provide a link to a reputable site.



  • rate this

    Comment number 162.

    @137 Umm, people with Physics degrees aren't any longer the best people to comment? Everything you've learnt is incorrect now surely, putting you on a level footing with the rest of us.

  • rate this

    Comment number 161.

    Vastly important IF they have got it right. What would mean will take a long time to work out. PLEASE let us not have a torrent of comment from non scientists about the philosophical implications.

    To post 16 Mike Solomons, yes the speed of light is supposed to be absolute and not dependent on earth's speed. If you want to know see http://en.wikipedia.org/wiki/Michelson-Morley_experiment

  • rate this

    Comment number 160.

    This is exciting stuff, but we should give credit to Dr. Ereditato and his team for their restraint in asking for the wider community to scrutinise the results. How many times have we had 'discoveries' trumpeted from the rooftops only to be disproved very soon after.

    Of course, I can't comment on findings without seeing the data first, but I'm optimistic that this may open new fields of study!

  • rate this

    Comment number 159.

    As the Pauli exclusion principle applies to these particles (no two particles can occupy the same space) maybe a simultaneous jump occurs when the Neutrinos change from muon to tau? If this is the case then why should it be tend more towards an increase in speed? Have any of the results shown a decrease on the speed of light?

  • rate this

    Comment number 158.

    The speed of light changes with the medium it passes through. It is usually taken as the speed of light through space and people assume that space is a vacuum. Space is full of different electromagnetic waves, which we know something about, gravity which we know little about and who knows what else that we have yet to discover.
    Scientific theories or laws should not be accepted as absolute truth.

  • rate this

    Comment number 157.

    Perhaps we've found something to join the effect first noted by Douglas Adams: "Nothing travels faster than the speed of light with the possible exception of bad news, which obeys its own special laws"

  • rate this

    Comment number 156.

    Science is not about coming up with the ‘right, unchanging, perfect, ultimate answer’ but better and better approximations to the ‘truth’.
    So, I guess it just goes to show Einstein was right, relatively speaking.

  • rate this

    Comment number 155.

    Congratulations, CERN! No, Einstein is not infallible, and never was. Foolish of humans to imagine any human can be infallible.

  • rate this

    Comment number 154.

    Particles are possibly observed to travel faster than light and the entire edifice of modern physics is promptly questioned - at it should be if proved correct. And then new theories will emerge consistent with observation.

    What a refreshing contrast to the unbelievable idiocy of religious dogma!

  • rate this

    Comment number 153.

    It's daft for us to say, "Ah, but did they think of this" or, "They forgot about that". These are professional nuclear physicists. Of course they considered it! This is a really interesting finding and they're doing exactly the right thing in throwing it open to the wider scientific community to attempt to find an explanation for what could be a momentous discovery.

  • rate this

    Comment number 152.

    I'm shocked: I'd expected most comments to point the finger of blame at climate change.

    More seriously, how nice to see a bit of science which the public might (sort of) understand being exposed in the way science ought to be pursued. Perhaps the prima donnas of climatology might take note.

    My physics and astrophysics degrees are 1970s vintage so I'm keeping out of the science :(

  • rate this

    Comment number 151.

    I don't know if its true or not, but the very fact that some scientists think it might be shows how little even the best minds really know. Yet- despite shaky science- evolution is preached as fact. Say it for what it is... a theory with many suppositions.

  • rate this

    Comment number 150.

    where is the link to the results, i'd love to have a look at such important results.
    my first question to check out would be have they assumed the the path of the particles follows a radius and not going from magnet to manet in a cross between an arc and an eliptical course

  • rate this

    Comment number 149.

    Probably just another software bug at CERN.
    They have been fixing large numbers of them recently, over 10,000 in a shared toolkit used to capture and store data for starters.
    See http://www.theregister.co.uk/2011/09/22/cern_coverity/

  • rate this

    Comment number 148.

    Ah! Perhaps that is why I keep getting in to work five minutes early each day. I'll have to adjust my atomic wrist watch!

  • rate this

    Comment number 147.

    I agree with Phil at 99 but I wouldn't say 'wrong' is the right word...


    and I too agree that 'wrong' might not be the right word ..lol

  • rate this

    Comment number 146.

    The speed of light is thought to a perfect natural constant. There is only one number that can be attributed to a perfect natural constant, and that is 1 (one). If you are theorising about quantifying energy and matter, Einstein’s theory should have been propounded as e=mc not e=mc2, as the square of a perfect one would still be one. Or am I missing something?
    Des Currie.


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