Saturday, June 16, 2012

Neutrinos, Still Not Faster Than Light, For Reals This Time

The first use of a hydrogen bubble chamber to detect neutrinos, on November 13, 1970. VIA: Wikimedia commons
Even people with no other interest in or knowledge of physics what so ever, are familiar with the concept that nothing can travel faster than light. This "cosmic speed limit" as it is often called, is based on Einstein's theory of special relativity, which, after now having stood up to over 100 years of experimentation, is one of the most tested, and well established facts in all of physics. So it's understandable why, when CERN published the results of an experiment late last year which seemed to show the sub atomic particle known as the neutrino might actually be capable of traveling faster than light, it was kind of a big deal.

The results in question were first published in September of 2011, after an experiment in which beams of neutrinos repeatedly fired (1500 times to be exact) from an accelerator in Geneva, managed to reach their destination in Italy a full 60 nanoseconds faster than should have been physically possible.

Not surprisingly, these results were met with skepticism  from the vast majority of physicists, who presumed they were likely due to an experimental error of some form, and would almost certainly not stand up to further analysis. Which wasn't a particularly surprising stance for them to take, given that actually confirming it to be possible for anything to violate the physical limits set by special relativity- yes, even by as little as 60 nanoseconds (60 billionths of a second)- would literally have redefined one of the fundamental rules of our reality as we now understand it. And sure enough, in February of this year an initial examination of the equipment used in the experiments, found that a combination of a faulty fiber optic connection and GPS unit, were most likely responsible for the result.

On June 8th, at the International Conference on Neutrino Physics and Astrophysics in Kyoto, CERN research director Sergio Bertolucci announced that the results of four new experiments designed to test the original findings. All of which, after correcting for the apparent timing errors in the original experiment, recorded a time of flight for their neutrinos that was under that of the speed of light. Thus making it official: Like every other known bit of matter in the universe, neutrinos, STILL can't travel faster than light.


VIA: Wired Science

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