We have recently posted about the two Cern experiments that seem to show neutrinos travelling faster than the speed of light. But what do the scientist think about it? We have pulled together some comments from one of our favourites – Prof. Jim Khalili, for your information. You can read the whole of his article here – Deskarati –
According to our understanding of the laws of physics, nothing can exceed the speed of light, an impressive billion kilometres an hour. And in my experience, there is nothing that annoys people more about Einstein’s theory of relativity (for that is where this notion originates) than its claim to this cosmic limit. Since Einstein’s work in 1905, thousands of experiments have only confirmed it – and indeed much of the beautiful edifice of modern physics rests on it being correct. The crucial point is not that light is so special but rather that this speed limit is written into the fabric of space and time.
But what if Einstein was wrong? Is there a way of understanding the findings of Opera? The whole point of a scientific theory is that it is there to be shot down – to be shown to be false by new experimental evidence, or to be replaced with a better, more accurate theory that explains more. But extraordinary claims require extraordinary evidence, and the scientists working on Opera – who cannot be faulted for the thoroughness of their experimental work – are the first to admit they have no idea how their result is possible. They also know where potential faults in the experiment still lie and, so far, they have ruled out one potential source of systematic error. But they admit there may well be others.
After the media hype claiming Einstein was wrong came the next twist in this drama. A rival experiment at Gran Sasso, called Icarus, also captured some of the Cern neutrinos, but it measured their energy rather than journey time. It had been pointed out by theorists very soon after Opera’s initial announcement that if the neutrinos were indeed superluminal, they would have to be emitting radiation throughout their journey and hence losing energy. Not doing so would be a bit like an aircraft that manages to break the sound barrier without a sonic boom. It just shouldn’t be possible.
The Icarus collaboration announced this week that they found no evidence of this radiation, since the neutrinos arrived at their destination with the same energy as when they had left. They could not have been travelling faster than light.