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 205.

    A Truth Fairy... The Higgs is predicted in virtually the identical way that the Top Quark was predicted and confirmed. When we had 5 out of the 6 predicted quarks to fix "charge-parity violation", we expected to find the top. Well, we did, in 1995 at Fermilab. Now, Fermilab's replacement hopes to find the last particle predicted by the standard model, the higgs. How is that a fudge?

  • rate this

    Comment number 204.

    Find this fascinating but not being a scientist struggle to comprehend the details. However if this may lead to time travel my wife will make a great person to test it out. Not told her yet but she'll be fine about it.

  • rate this

    Comment number 203.

    153. David W 16 Minutes ago

    It took Einstein, working in a patent office to make more sense of the world last time, maybe a blue collar worker will make more sense of it this time

    It's daft for us to say, "Ah, but did they think of this" or, "They forgot about that". These are professional nuclear physicists.

  • rate this

    Comment number 202.

    Since speed is relative to it's surroundings and assuming the CERN scientists have calculated earth's rotation etc correctly there can really only be one answer, someone left the door open and caused a draft.
    Seeing how some of them drive to work, totally possible.

    Seriously though, I suspect this will be un proven. Probably the method of measurement will be found to have a flaw.

  • rate this

    Comment number 201.

    I notice editors' picks seem to be the comments which have provoked a lot of pluses or minuses; the problem with this is that the ones with the most negatives are likely to be the most inane, but now they're the first ones readers will see.

  • rate this

    Comment number 200.

    If this discovery is proven to be correct it will upend decades of scientific 'certainty'. It will also open up countless other possibilities. Inter-stellar travel, for instance and maybe even time travel.

    Odd, is it not, how science fact seems to lag behind science fiction but ultimately proves the latter, once thought impossible, to be entirely possible.

    This story is one to watch.

  • rate this

    Comment number 199.

    There's something fundamentally wrong with physics - things don't stack up and ever more complicated fudges are required to try to explain things. Dark energy/matter, HIggs bosons etc. When things get like this, you have to question the most basic assumptions - and the speed of light being constant is one of the holiest. This may just open up the possibility that it isn't !

  • rate this

    Comment number 198.

    Umm, 193, there's about 100 years of empirical research on the subject that tends to disagree with you. Einstein's special relativity is just about the best tested scientific theory we have out there. From c being measured constant, to ridiculously accurate time dilation measurements, I mean, even GPS satellites rely on relativistic corrections to keep accurate. Relativity is as tested as you get

  • rate this

    Comment number 197.

    For the record... FIRST!

    I have a conventional computer that follows the conventional laws of physics so if this post arrives later than the show off's above me then don't give me any crap about it.

  • rate this

    Comment number 196.

    There is an old saying in scientific circles. "When a distinguished and highly qualified scientist declares that something is possible, he is probably right. If he declares that something is impossible, he is almost certainly wrong."

  • rate this

    Comment number 195.

    couldnt they check by sending a Neutrino and some light down the same route at the same time and see which one got there first, just to see if it was an error?

  • rate this

    Comment number 194.

    How was the distance between the labs measured?
    This region is cut by numerous semi active and active thrust faults as Africa approaches Europe. The distance is decreasing marginally over time, perhaps mm per year.

  • rate this

    Comment number 193.

    We need to remember that the basis for Einstein’s theory has always been in the area of theoretical physics. This means that scientists/mathematicians build mathematical models to explain a theory. Practical investigations are therefore needed to investigate these models. We are now entering an era where applied physics is able to investigate the extremities of these mathematical models.

  • rate this

    Comment number 192.

    I love it when comments have the lorentz factor in them. It means some people really do care about physics, more than just "I heard about the double slit experiment, pretty crazy stuff man!"

    The world needs more physics students.

  • rate this

    Comment number 191.

    I find it hilarious how many people are coming on here and dismissing this out of hand without having any understanding (eg light travels at different speeds through rock). If you are going to argue, at least get a basic understanding first. Personally, I find this exciting either way. If it is faster than light then it challenges all of physics. If not, the explanation should be interesting.

  • rate this

    Comment number 190.

    @163 Ben

    "They have not been disproved" ... like the US didn't lose Vietnam, "It was a tie" !!!!

    Okay, lets just say that scientists refuse to accept Quantum Physics because they would all be out of a job, and instead spend all their time coming up with elaborate reasons why they don't have to - so they can keep their job.

    It was tough getting the world to see the Earth wasn't flat, too.

  • rate this

    Comment number 189.

    The speed of light is nearly 3*10^8 m/s; the Opera collaboration states that the neutrinos appeared 60 ps too early. There are 10^12 ps per second, so light travels 300 um per ps. So if it were a race, the neutrinos would beat the light by18,000 um, or 18 mm - 3/4 of an inch.

    The error must be in how they calculated the distance ... they are off by 18 mm out of about 450 km. GPS error?

  • rate this

    Comment number 188.

    My thought is perhaps a pressure or "bow wave" building up in front of the neutrinos. It would arrive ahead of the main body, but would not be travelling any faster.

  • rate this

    Comment number 187.

    in my view,there might have been some errors or its even possible that the nature of possible errors that might arose at such level of speed is still to be discovered.i mean theoretically we have equations that tells us an object would have an indefinite mass if it tends to approach the speed of light.m'=m/(root(1-(v^2/c^2))furthermost it will be crazy if mass will be complex.

  • rate this

    Comment number 186.

    Just to repeat what has already been posted earlier (#75). The link to the paper produced by the researchers is:


    "Measurement of the neutrino velocity with the OPERA detector
    in the CNGS beam"

    Great to see so many people taking an interest in science!


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