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 225.

    There's a lot at stake here and it is absolutely right to challenge the data and make sure they are valid before going back to the theoretical drawing board. However, if the results do stand up we could see a huge shift in Physics. Hats off to the investigators for expressing true doubt and inviting criticism.

    This is how science should be done.

  • rate this

    Comment number 224.

    Brilliant. It would be great to see a sundamental constant of the basis of modern physics turned on its head.

    Maybe they can put their efforts next into a toaster than toasts perfectly both side every time - or is that an impossibility like going faster than the speed of light :)

  • rate this

    Comment number 223.

    rideforever: Aren't you delighted that science revisits established theories and supercedes them when new findings come to light? Show me a better way of thinking.

  • rate this

    Comment number 222.

    Actually Martinll, this is in Switzerland where even the trains arrive early, which as a Brit I find even more shocking.

    9 Minutes ago
    Errr....something arrived EARLY...in Italy?? .....shome mishtake shurely.....

  • rate this

    Comment number 221.

    Could this not just mean that light too suffers from friction and also cannot reach the 'ultimate speed'?

  • rate this

    Comment number 220.

    Relativity does allow faster than light travel. The object just needs to be travelling faster than the speed of light to begin with.

  • rate this

    Comment number 219.

    So, if CERN broke the speed of light, who fixes it?

  • rate this

    Comment number 218.

    Don't worry everybody.

    Just ask Usain Bolt for the answer.

    He will know.

  • rate this

    Comment number 217.

    Further, this means, in case the readings ring true, that we'll either have to throw away the theory of relativity OR amend it so that we more properly can portray the speed of light and FTL speeds in a new sense. This is a very sensational discovery, if it proves to be true.

  • rate this

    Comment number 216.

    speed of neutrinos is 3*10^10m/s

  • rate this

    Comment number 215.

    The article is incorrect when it says that nothing can exceed the speed of light. Things can exceed the speed of light - the beam of an oscilloscope across the screen for example - what is important is that no useful information can travel faster than light.

  • rate this

    Comment number 214.

    It's a shame to see so many ill-informed self-opinionated rubbish posted in these comments.

    It stated in the article that the experiment has been repeated many times, achieving the same result, that's what statistical confidence indicates. The experimenters are quite right in asking for help in double checking such potentially important results.

  • rate this

    Comment number 213.

    Errr....something arrived EARLY...in Italy?? .....shome mishtake shurely.....

  • rate this

    Comment number 212.

    It's not right that the speed of light cannot be exceeded. It is highly possible, the theory of Einstein, E=MC^2 only states that an object with MASS may not move at the speed of light. However what has happened here is that an object with mass, the neutrino, has moved FASTER than speed of light, which "breaks" the basic rule of the theory of relativity.

  • rate this

    Comment number 211.

    Clearly, the error is caused by distance contraction. The 450 miles traveled is from our point of reference. From the Neutrino' standpoint the distance traveled is shorter (twin sister to and from outer space phenomenon. This distance contraction = mathematical speed distortion. Plus, the mass of the neutrino, on average, spontaneously becomes - at its emission point.E=MC2 only pertains to + mass.

  • rate this

    Comment number 210.

    Revolutionary if proven true, but probably a bit too early to get too excited. Anyone recall the flurry of excitement caused by the cold-fusion claim from the early 1990s?

  • rate this

    Comment number 209.

    Re: 16 Mike Solomons. It is absolute. The ultimate invariant, and without overstating the fact, literally the whole universe is based on that fact.

    I am more interested in how they are detecting neutrinos in such numbers. They don't interact with 'normal' matter to speak of. Billions upon billions have passed through you from the sun whilst you read this.

  • rate this

    Comment number 208.

    Stop, E = MC Hammertime

  • rate this

    Comment number 207.

    @ 178.alan howarth:
    You may have a degree in physics (do you really?) but you haven't got any manners. If you want to be among peers only, don' come here. I haven't got a clue about science / physics, but I enjoy the subject matter and prefer not to have that ruined by a miserable curmudgeon.

  • rate this

    Comment number 206.

    This is the thing I find so fascinating about science. As Tim Minchin put it, "Science adjusts it's views based on what's observed". This discovery could one day change our understanding of the universe and the way in which things work. Doesn't meant previous scientists were wrong; all science is build on the foundation of others work. That's not arrogance, it's a thirst for knowledge.


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