In September, the science world was left in shock when workers at the world’s largest physics lab announced they had recorded subatomic particles travelling faster than the speed of light. Now, measurements by an opposing team of physicists suggest neutrinos cannot have travelled faster than the speed of light.

After performing their own tests, the researchers, who share the same lab as the team that made the original findings, have joined other physicists’ skepticism about whether or not something can in fact travel faster than the speed of light.

According to the Guardian:

In September, physicists working on an experiment called Opera at the Gran Sasso laboratory in Italy announced that neutrinos sent there from Cern near Geneva seemed to complete the 720km journey faster than a beam of light.

These same physicists seemed to prove their findings again on Friday, raising more questions about Einstein’s theory of special relativity – that would allow information to be sent back in time – and thus create confusion with the concept of cause and effect.

The Guardian continues:

But measurements by a competing team of physicists at the Gran Sasso laboratory now suggest the neutrinos cannot have travelled faster than the speed of light as they hurtled through the Earth from Switzerland to the Gran Sasso lab near Rome in central Italy.

The team, who work on an experiment called Icarus, tested an argument described in a recent paper by Andrew Cohen and Sheldon Glashow at Boston University [both part of the team of original physicists], who argued that faster-than-light or “superluminal” neutrinos would lose energy by spewing out electrons and their antimatter partners called positrons. Professor Glashow shared the Nobel prize for physics in 1979.

When Maddalena Antonello and others on the Icarus team analysed the energy of the neutrinos arriving at Gran Sasso, they found no evidence that they had lost energy the way Cohen and Glashow predicted. The finding has bolstered the view of many physicists who believe the Opera result is an error of measurement.

A professor of physics at the University of Surrey, Jim Al-Khalili, who said he would eat his boxer shorts if the original findings were found to be true, sums it up rather well:

Opera measures the time of neutrino travel and hence their speed, whereas Icarus – who also detect the same neutrino beam – measure the spread in energy of the arriving neutrinos. They found that the neutrinos don’t lose energy on their route. The problem of course is that they should do, if they were travelling faster than light.

This is the equivalent of the sonic boom when something goes faster than sound. Usually we see this effect when particles go faster than light through transparent media like water, when light is considerably slowed down. It’s called Cerenkov radiation.

So these neutrinos should have been spraying out particles like electrons and photons in a similar way if they were going superluminal – and in the process would be losing energy. But they seemed to have kept the energy they started from, which rules out faster-than-light travel.

So, after carefully reading and breaking through all the jargon, whoever wants to be right, is going to have to continue with more experiments.

[Source: Guardian]