So CERN has stunned us with a result and this one doesn’t even come from the LHC. The premier European high energy research institute has detected neutrinos that seem to move at a speed greater than that of light, violating one of the most sacred pillars of physics – Einstein’s Special Relativity. You must have read about it – we posted it here. So what about these faster-than-light neutrinos? Why are so many people all excited about them?
In this article, I will try and explain that, touching upon four crucial points. First we need to understand why people are not ready to believe the result in the first place. Next, we’ll understand whether this is believable or not. Is CERN just tricking us or have they put real hard work behind this before publishing it? Next, we shall talk about the implications of this result, if it is proved right. Lastly, we discuss how there can still be flaws and where some glitches might be found in the coming days.
Unlike the popular media, scientists are treading softly on this result. They are not yet ready to say that Einstein was wrong, although that is what it would imply. They are merely reporting facts at this moment, stating the results as got in the experiment. The result is very possibly wrong, but let’s take a closer look.
What on earth are Neutrinos?
The real heroes of this story, Neutrinos are the slipperiest of all known particles. They carry no charge, almost no mass and interact extremely feebly with other matter and that too via the weak interaction. They’re nearly impossible to detect. They leave no tracks in bubble chambers (no charge), don’t interact with each other to form clumps (no strong interactions, like those of protons and neutrons) or speak with normal matter particles. Scientists were forced to assume its existence to solve a puzzle (the beta decay problem), and, even though neutrinos have been detected after that by several detectors, their properties remain largely mysterious. They are giving a headache once more.
Why are people not ready to believe it?
Simply put, it’s Einstein. People are not expecting anything new and now they find this! This is just too unexpected. Why take a result so flagrantly conflicting with all known physical results at face value? Well…
Is this result Believable?
As an answer the first of our questions, I would go with a ‘Yes’. The result is totally believable in the sense that the experiment and analysis seem water-tight at this moment. Scientists of the OPERA collaboration have been looking at the data for three years! They have done everything scientifically possible to discredit their own finding, but have only managed to strengthen it.
Remember, we told you in the particle physics articles, what confidence level means? A confidence level, quoted as some n-sigma, ‘n’ being an integer, refers to the amount of confidence the experimenter has on his/her own results. A 3-sigma result is one which is significant enough to be considered a potential for ‘detection’. This means that the doubts are less than 0.3%. We’re just getting warmed up! For a ‘discovery’ we need a minimum of 5-sigma, which is a confidence level of 99.9999%.
The current results are a 6-sigma, at 99.999999% confidence level, high and above the threshold required to get a ‘discovered’ tag!! This still doesn’t mean that it is true. It just means that the possibility that this is merely a statistical fluctuation is extremely small. They two are very close, but not the same.
The real motivation for believing in what CERN has found is the methodology they’ve applied in finding out the results. They had found this result 3 years back, but never jumped the gun in publishing it. They checked and re-checked everything, found crucial error bars and found that this result survives. They added more parameters contributing smaller errors, hoping that they’ll somehow add up and then give the ‘necessary’ error bars. They didn’t.
We’ll just talk about the use of GPS and cesium atomic clocks to measure time and how accurately the distance was measured. Since velocity is simply distance divided by time, we need both parameters accurately.
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