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 25.

    Particles can appear to travel faster than light. In order to know the speed, you must know the distance. When we talk about subatomic particles we talk about a different definition of space and distance. Space is not linear or flat. Light can travel on the 'surface' of space while another "particle" can tunnel through the 'hills' of space. Same "speed" different distance. One SEEMS to be faster.

  • rate this

    Comment number 24.

    I believe if the scientists in CERN are a lot more humble about what human knows just by looking at the experiments they are doing there.
    If you are a scientist working in that tube....you already realize one thing.
    Everything we know since we began till now is only 4-5% of what the universe is. We don't even know why we have weight. It SHOULD be humbling

  • rate this

    Comment number 23.

    Mike Solomons The speed of light is supposed to be a constant, not relative to anything. At whatever speed you yourself are travelling with regard to the light source, your measurements will always give the same result for the speed of light.

  • rate this

    Comment number 22.

    We thought you could not exceed the speed of sound too. As speed increased, so did drag, and at the speed of sound, you would have infinite drag. At the speed of light, in theory, you should have infinite mass. As you approached the sound barrier, drag did go up exponentially, to a point, and then dropped down. It peaks again at Mach 2. So perhaps mass does the same @ speed of light?

  • rate this

    Comment number 21.

    No, they did not measure any particles traveling faster than light. Since when can they measure neutrino's? If the distance between CERN and Gran Sasso as it cuts through the Earth is not exact to within a few atoms, or any other parts are off by just a bit, then multiply those errors and you get International Embarrassment and Ridicule. Dopes.

  • rate this

    Comment number 20.

    Great to see science in action!

  • rate this

    Comment number 19.

    An important finding as far as scientific results are concerned. May be space scientists will find it a new discovery for the vast set of calculations they use to measure great distances between stars and planets. They should move on and bring some other facts into light as well before proving the most fundamental concept of Light speed to be outdated.

  • rate this

    Comment number 18.

    The speed of light is written into the core of physics as an ultimate speed limit. bizarrely it never matters what you are measuring it against, whether you are moving, how heavy or light an object is, nor what other people see, the rules as we understand them forbid this result being true.

    This is why the authors are so confused by the result, if true then much of science needs a rewrite!

  • rate this

    Comment number 17.

    If you look at discovery's made over the past 100 years, it's highly likely we're soon going to discover something that will change physics for ever.

  • rate this

    Comment number 16.

    Speed in relation to what? Is the speed of light supposed to be absolute or relative to its immediate surroundings? Remember the test route is travelling in space due to movement of the earth.

    Maybe the calculations need to include speed of rotation of the earth, rotation around the sun, and movement of our solar system in space.

    Or maybe Einstein's theories were incomplete.

  • rate this

    Comment number 15.

    Exciting news! I have 2 books speaking of Einstein's own equation E=mc2 that shows the ability to exceed the speed of light: to set aside complicated physics,we are taught that 'c2' or 'c squared' is 'c' multiplied by 'c'; and if not..is '2squared' still equal to '4'? Einstein paved the way, quantum goes beyond, reaching into realms until now reserved for the spiritual=Science and Spirit together.

  • rate this

    Comment number 14.

    I think this is great, great research.

    But in recent years the arrogance of scientists has left a bad taste in that profession - they have lost their humility and started telling the world that they know better.

    They don't actually know anything for sure, and what they think they know changes every 5 minutes.

  • rate this

    Comment number 13.

    Einstein published his Theory of Relativity in 1915 . Neutrinos were not discovered until 1956 so why should it be so difficult to imagine that they can travel faster?

  • rate this

    Comment number 12.

    You mean Meatloaf might have been right afterall!

  • rate this

    Comment number 11.

    When was the last time they check the speed of light?
    It might be slowing down making the Muon Neutrinos look faster?

  • rate this

    Comment number 10.

    Bang goes the Theory.............. And why not????

  • rate this

    Comment number 9.

    This result is inconsistent with all modern physics, since Einstein published his Special Theory of Relativity in 1905. It is also suspicious that such fast than light neutrinos have not been detected before, as they have been studied extensively.

    Clearly the data is somehow wrong, and the results are a product of a flawed experimental set-up or calculation.

  • rate this

    Comment number 8.

    I don't understand the negative comments here about the scientists' method. They have seemingly found a result that runs contrary to one of the most basic presumptions of modern physics - by a few billionths of a second - so they want to get it corroborated before jumping to conclusions. Seems like they've understood the spirit of the scientific method perfectly.

  • rate this

    Comment number 7.

    What speed did they do? It wasn't Warp speed was it?

  • rate this

    Comment number 6.

    RE. NOT YOU .... It ain't you!
    As for traveling faster than the speed of light? Just proves we no so little about so much. We seem to forget one major thing and that is we are just so minute in thewhole of infinity/space that we will never live long enough to no of anything of major importance. Our time here to date is less than nothing and our time left is about the same! We just screw up LIFE!


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