A second experiment confirms what physicists have been both dreading and hoping for: Neutrinos are travelling faster than the speed of light. 

Unbeknownst to many of us, the field of physics was turned on its head last September, perhaps irrevocably. Physicists the world-over have been alternating between pulling their hair out and jumping for joy, all while pinching themselves to make sure they aren’t dreaming. This is because of an experiment that demonstrated that neutrinos, very light subatomic particles affected only by gravity and the weak force, were moving faster than the speed of light. This assertion has shaken the very foundations upon which post-Einstein physics rests and could lead to a physics revolution.

Before going any further, however, here’s a physics primer to get us all up to speed (pun intended). Most of us are familiar with Einstein’s famous equation E = mc², in which “c” is the speed of light (299, 792, 458 m/s). This equation demonstrates that, as the energy of an object increases, so does its mass, thus causing it to resist acceleration. Now, according to Einstein’s theory of relativity, an object can never reach the speed of light. Renowned physicist Stephen Hawking explains this in his book, A Brief History of Time, by stating that in order for an object to attain the speed of light, its mass would have to become infinite and the energy needed to get there would also need to be infinite– an unlikely scenario to say the least.

So when the OPERA collaboration, an international group made up of about 200 physicists from 13 different countries, declared in September of 2011 that they had clocked neutrino speeds exceeding the speed of light, the ensuing uproar was deafening. Scientists the world over denied the possibility of particles moving faster than light and questioned the science that had led to this result. For example, physicist Carlo R. Contaldi of the Imperial College London, UK, published a letter stating that there must have been a mistake in the clock synchronisation convention the OPERA scientists had employed.

“If the OPERA results were confirmed, it would be truly earth-shattering. However, the community at large, while respectful of the OPERA team and their procedures, remains skeptical of the implications of the result,” commented University of Guelph physics professor Dr. Paul Garrett.  ”Relativity has been so well tested over the past 100 years that people are not yet willing to abandon it.”

The many objections, combined with their own doubts, motivated the OPERA collaboration to conduct a second experiment in which they would refine their analysis of the data.  The results of this experiment, which were released on Nov. 17 2011 as a preprint for the Journal of High Energy Physics, confirmed the original findings. In this second experiment, the researchers detected 20 neutrinos that had travelled a distance of 730km in 2.43 milliseconds, about 60 nanoseconds faster than light, with a margin of error of 10 nanoseconds.  This time the results were robust enough to make the scientists, who had previously refused to sign their names to the paper, reconsider.

Do these experiments prove Einstein wrong? Not yet. More tests needs to be done, this time by a group of researchers independent of the OPERA collaboration and hopefully using different equipment and data. In addition, there are many possible sources of error– most of them having to do with the synchronisation of the time reference– that need to be eliminated through further experimentation. In the meantime, the resulting collective loss of sleep that will be experienced by the global physics community is probably the only part of this saga that need not be questioned.

Arielle blogs about science at www.salamanderhours.com

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