The speed of light appears to have been broken again after scientists carried out a new set of experiments to test measurements that could require the laws of physics to be rewritten.
Scientists have posted new results that confirm measurements made in September that a beam of subatomic particles had travelled faster than the speed of light.
The initial result caused widespread debate as it appeared to break one of the most fundamental laws of physics – that nothing can travel faster than the speed of light.
The findings have proved troubling for scientists as it goes against Albert Einstein's law of special relativity and opens up the possibility of being able to send information back in time.
The researchers behind the experiments, which involved sending neutrino particles 450 miles through the ground from the CERN facility in Geneva to the Gran Sasso laboratory in Italy, have now attempted to rule out one possible source of error.
By tweaking the experiment in an attempt to address a potential flaw in their original experiment, they again showed that the neutrons arrived at the Italian site some 60 billionths of a second faster than if they had been travelling at the speed of light.
The European Organisation for Nuclear Research, or CERN as it is known, said: "This test confirms the accuracy of the timing measurement, ruling out one potential source of systematic error.
"The new measurements do not change the initial conclusion.
"Nevertheless, the observed anomaly in the neutrinos time of flight from CERN to Gran Sasso still needs further scrutiny and independent measurement before it can be refuted or confirmed."
When scientists announced they had measured neutrinos apparently breaking the speed of light in September the result drew mixed reactions from scientists.
Professor Brian Cox, a particle physicist at the University of Manchester and TV presenter, said it would be the most profound discovery in physics for more than a century.
Fellow TV presenter Professor Jim Al-Khalili, a physicist at University of Surrey, said that if the findings were proved to be correct, "I will eat my boxer shorts on live TV".
Speaking after the most recent announcement, Professor Al-Khalili said: "I am not yet ready to get out my knife and fork.
"The results have dealt with some possible errors. There are still a number of other possible errors and uncertainties that they are working on ruling out."
The scientists behind the experiments, who are part of the Oscillation Project with Emulsion Tracking Apparatus, or Opera, collaboration, had conducted more than 15,000 measurements over three years before announcing their results.
They used 10 microsecond long pulses of neutrinos in the initial experiment, but other scientists pointed out that this could be a potential source of error as the pulses were relatively long compared to the difference in time being measured.
In the new test they used shorter pulses of neutrinos, at around three nanoseconds, so they could time the arrival of the neutrinos with greater accuracy.
When the Opera team ran the improved experiment 20 times, they found almost exactly the same result.
It has been posted to the Arxiv repository and submitted to the Journal of High Energy Physics, but has not yet been reviewed by the scientific community.
Fernando Ferroni, president of Italian Institute for Nuclear Physics and spokesman for the Opera consortium, said: "A measurement so delicate and carrying a profound implication on physics requires an extraordinary level of scrutiny.
"The positive outcome of the test makes us more confident in the result, although a final word can only be said by analogous measurements performed elsewhere in the world."
Other groups of scientists are now also working to repeat the findings independently and a consortium of American, Russian and British scientists are planning to send neutrinos from a laboratory in Chicago to the Canadian border to test the results.
Dr Giles Barr, a physicist at Oxford University who is involved the experiments in the US, said: "It's a very intriguing result. The thing that is needed is for more physicists to independently verify what is happening.
"They have done a very careful job of this and trying to look at all the individual details that could fake this effect. They couldn't find anything. It is fantastic.
"They have brought up some other tests they can do to check what is happening and the checks have shown what you might expect if the neutrinos are travelling faster than the speed of light.
"We are going to try to do it ourselves."
He added that if proved correct it could have some profound implications for the current understanding of how the universe works.
He said: "We have this notion from Einstein himself that particles cannot travel faster than the speed of light – that light itself is the thing that travels the fastest.
"The profound thing that could happen here is that some people in a very fast spaceship could actually observe these neutrinos leaving after they have arrived in the place where we have seen them.
"In other words time could be travelling in reverse. It is a very mind boggling thing."
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