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 105.

    no. 85
    "The guys at CERN are good and are asking that intelligent people review them. Don't call them dopes."

    I thought that they were suppose to be more intelligent!!

    as mentioned earlier how do we know for sure that Einstein was right in his assumptions in the first place?

    maths and how we accurately calculate (decimal places etc.) things has improved considerably since his time.

  • rate this

    Comment number 104.

    Thank you, Dougie Lawson (comment #75) for the most useful contribution so far.

    Either we learn something fundamental about the universe or we learn something else about experimental assumptions; or perhaps something else as yet unthought-of. Why aren't we spending much more money on fundamental science instead of new ways to kill one another?

  • rate this

    Comment number 103.

    #Told you so
    I'm delighted.This makes the big bang, missing dark matter and gravity make much more sense. It removes a very inconvenient restraint----------
    You couldn't be more wrong- the special theory of relativity has been used to postulate the Big Bang THEORY- remove it and everything about that theory is complete guess work. However inconvenient gravity has been proven by experimentation.

  • rate this

    Comment number 102.

    I have no idea why the big brains at Cern and Gran Sasso didn't just pop onto this link for their solutions ... staggering responses here have really put a smile on my dial this morning, thanks!

  • rate this

    Comment number 101.

    As with all 'speed timings' a time for the return trip is required to verify the first result. If the return trip from Gran Sasso back to Cern exeeds lightspeed by the same ammount then the results are correct.

  • rate this

    Comment number 100.

    Hello everybody! I remember one or two years ago a scientist at Harvard could reduce the speed of light by freezing the particles. I believe that higher speeds than that of light could be achieved depending on the particle size and force of attraction, just why should not; every particle has mass and consequently is subdued to the effect of different forces acting on it.

  • rate this

    Comment number 99.

    Almost certainly Einstein was 'wrong', just as Newton was 'wrong' before him and Aristotle before that.

    I take the point, that some have made, that some recent science has become arrogant (particularly around the global warming issue), hence we all need to recognise that our understanding is furthered by finding anomolies in known 'facts'.

    Congratulations to all of the team at Cern.

  • rate this

    Comment number 98.

    Don't panic!

  • rate this

    Comment number 97.

    They should send my girlfriend on the ride with them. It wouldn't take them any longer.... but it'd seem like it.

  • rate this

    Comment number 96.

    I'm not gonna make my mind up until I hear what Bill O Reilly and Glen Beck have to say about this...

  • rate this

    Comment number 95.

    It is interesting to be fair and kinda hard to get your head around. It does amuse me though when they say something like: "This could have devestating consequences.... obviously! And you sit nodding your head thinking....Obviously!

  • rate this

    Comment number 94.

    For those interested, check out the CERN press release at

    The results will be presented at a webcast seminar this afternoon.

  • rate this

    Comment number 93.

    Physics has some way to go on the Today Programme. We learned this morning that today is the autumnal equinox – "at least in Japan".

  • rate this

    Comment number 92.

    I personally don't believe Albert Einstein's theory that light travels at the fastest speed! We live on earth, it revolves around the sun at about 67000 mph. Do we feel the speed? NO! Now, suppose the universe is in motion, say at a constant speed of 100 times the speed of light, and we live in it, would we feel its speed? No, because we can only feel the change in speed.(continued in 2nd comment)

  • rate this

    Comment number 91.

    (continued)...Now the question is: Is the universe in motion? If yes, then the speed of light is not the fastest, because we don't have a reference point out side the universe to calculate our actual speed. Even if we do find that point after a million years, how do we know that the point we have discovered is stationary? So, I think there is no speed limit!

  • rate this

    Comment number 90.

    a few billionths of a second sooner, thats less than a meter, and over 732km, thats some accurate distance measurement!. maybe they measured to the wrong side of the bench.

  • rate this

    Comment number 89.

    Bad news travels faster than light

  • rate this

    Comment number 88.

    Suppose a neutrino is travelling at the speed of light and somehow generates another, wouldn't the second create the illusion of travelling at up to 2 times the speed of light? Probably not, but I suspect that something like this could be a useful start point for working out what's happening.

  • rate this

    Comment number 87.

    This is certainly fascinating and I think it's VERY positive that CERN are simply releasing the data to the wider scientific community with a plea for help in understanding it.

    Perhaps this could lead to a breakthrough. Perhaps it's nothing more than a glitched sensor.

  • rate this

    Comment number 86.

    Einstein believed that you woul arrive before you left.
    Of course you would because as an observer standing from the arrival point the light from your arrival point will arrive to the observer quicker than that of the departure point Due to the shorter distance.
    We must stop looking at barriers if the one thing in science we have learnt the only barrier is the barrier of our perception.


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