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 245.

    Mike Solomons "Speed in relation to what? Is the speed of light supposed to be absolute or relative to its immediate surroundings?" VERY good question! It's kind of both, while still having the same value (in a given medium) whichever way you measure it. That's what is so revolutionary (to our 'common sense' experience of the universe) about Relativity.

  • rate this

    Comment number 244.

    Didn't Tesla prive back in the 1920's that Tachyons can travel up to 27 times the speed of light? I still have the "New Scientist" magazine with this article in it. So why are people so suprised that yet again Tesla has been right!

  • rate this

    Comment number 243.

    This could be a significant breakthrough in science, if nuetrinos can reach faster speeds than light than that could mean that it might be possible for vehicles to move faster than ligh (just a possibility). SOrry about spelling im rushing.

  • rate this

    Comment number 242.

    They say "nothing" can move faster than light, Neutrinos are essentially "nothing" as they are tiny part of a tiny atom. So its good result. I really love to see the conclusive results after all calculations.

    Get ready for Warp drives, folks. :P

  • rate this

    Comment number 241.

    This is truly amazing. Part of me hopes that the team is proven right, as who knows what discoveries may follow. But equally, part of me hopes it is a mistake just because it is such a huge change to the world as we know it...

  • rate this

    Comment number 240.

    I've never understood how we could be so sure that nothing could travel faster than light. Some of the comments here have explained it better than ever before. Nonetheless I would still put my money on the complexities of our universe throwing up new discoveries and phenomena that will prove even Einstein had a lot left to learn. My money is on the universe over academic 'certainties'!

  • rate this

    Comment number 239.

    Half of me thinks it would be preferable that they find some mistake, so we don't have to alter modern physics and set us back a century...

    ...but then the other half thinks, damn, if they've just discovered a fault that was so ingrained in our picture of physics, that would be quite an astounding time to live in...

  • rate this

    Comment number 238.

    A Truth Fairy- It hasn't been found because it's a very heavy particle with a much lower probability production mechanism. So you need much higher energy particle colliders to find it. The LHC is still only at half of it's 7TeV per beam output, and the Tevatron was only 1TeV per beam, so what makes you think we should have seen it by now? Why is it more of a fudge than the top quark was?

  • rate this

    Comment number 237.

    I appreciate this experiment..............

  • rate this

    Comment number 236.

    An interesting article, I hope the BBC keep track of it so we can find out the results from the peer review. As for the reporting of science in the news http://urlybits.com/2009/08/how-science-reporting-really-works/ (may contain words some readers find offensive)

  • rate this

    Comment number 235.

    Science isn't an exact science as we set yet again. I love stories like this just so I can imagine the look on smug Dicky Dawkins' face! God bless him.

  • rate this

    Comment number 234.

    Oh yes the arrogance of these scientists, always trying to prove themselves wrong, who do they think they are trying to push the boundaries of our knowledge.

    Just to set the record straight, science dose not stop because we think we know the answers, the idea of science is to try and prove those answers wrong...arrogance my foot.

  • rate this

    Comment number 233.

    Einstein's relativity replaced Newton's gravity, which was the answer to the ultimate question until someone realised that Newtonian physics was just part of a much bigger picture.

    There are cracks and holes in the theories - dark matter theory is good example of the kind of sticking plaster that is currently needed, and is strangely reminiscent of the 19th century luminiferous aether theory.

  • rate this

    Comment number 232.

    I find it hard to believe that that have enough events and that they can be measured accurately enough to be able to produce a convincing result and that systematic errors are behind this. But you never know, so let the rest of the community review the findings and replicate the result. If so, it would be as groundbreaking as the Michelson-Morley experiment in the 1880s.

  • rate this

    Comment number 231.

    Zaold - predicted, but not found yet, eh ? Science should not be a religion where unpalatable evidence is just dismissed as erroneous and detractors treated as potential heretics. I am well aware of the maths behind c being constant, but, really, the Higgs mechanism is just too complex to explain why everything has mass and thus gravity, especially as it is proving incredibly elusive.

  • rate this

    Comment number 230.

    Lets be realistic here, is this really a surprise? We know next to nothing about the universe and the underlying physics. Imagine a cockroach trying to comprehend rocket science, that is us humans trying to understand the components that make up this great world and planet we live in, afterall It was roughly 1400 years ago that we still accepted that we lived on a flat earth.

  • rate this

    Comment number 229.

    After reading Hawking's "A Brief History of TIme" - particularly in relation to black holes - it struck me that if some particles are able to escape black holes as Hawking claims and if I remember well Hawking thought these were neutrinos also - then it is theoretically possible that particles can move faster than the speed of light if, as Hawking states, black holes capture light.

  • rate this

    Comment number 228.

    Al-canfor "So how exactly did Einstein come up with that speed of light limit?"

    To accelerate a particle with mass from rest to any speed requires energy. If you use Einstein's theory of relativity to calculate the energy needed to accelerate a particle to the speed of light it is infinite. You cannot have infinite energy hence you cannot reach the speed of light.

  • rate this

    Comment number 227.

    I really hope Physics isn't wrong... Otherwise the next two years of my degree are a bit outdated! :)

    I like that they're letting the international community have a look, I'm going to take a punt and say that it might have something to do with the fact that the particles are not travelling through a vacuum, and therefore can go faster than light would in the same materiel.

  • rate this

    Comment number 226.

    “Today's scientists have substituted mathematics for experiments and they wander off through equation after equation and eventually build a structure which has no relation to reality” Nikola Tesla


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