Physicists urge caution in faster-than-light finding | Science| In-depth reporting on science and technology | DW | 23.09.2011
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Physicists urge caution in faster-than-light finding

Scientists are shocked at the announcement of superluminal neutrinos. If true, the result would upend one of the cornerstones of physics – Einstein's theory of relativity.

A beam of light from a satellite

Physicists are cautious to say that the speed of light has been broken

It's not everyday that scientific experiments throw up a result that has the potential to challenge one of the most fundamental rules of modern physics.

But that's what happened when researchers from the Oscillation Project with Emulsion-tracking Apparatus (OPERA) experiment announced on Thursday that they had unveiled evidence that fundamental, mysterious particles – known as neutrinos – had exceeded the speed of light.

Scientists sent a large amount of neutrinos from a particle accelerator at CERN, outside Geneva, where they were created, to the Gran Sasso laboratory in Italy, 723 kilometers (450 miles) away.

The 16,000 detected particles arrived 60 nanoseconds sooner than the time normally predicted by the speed of light.

OPERA spokesperson Antonio Ereditato

OPERA spokesperson Antonio Ereditato presented the new findings at CERN on Friday

The OPERA team found that their neutrinos travelled 300,006 kilometers per second, which is just above the established speed of light, which is usually measured at 299,792 kilometers per second.

'Sensational results need sensational proof'

While the finding has rocked the scientific community, many researchers in Europe say they're a bit skeptical at this stage at the preliminary outcome.

"It's a pretty amazing result if it turns out to be true," said Ask Emil Jensen, a particle physicist and doctoral student at the Niels Bohr Institute in Copenhagen, in an interview with Deutsche Welle. "It's something that goes against everything that we've believed in for the last 100 years."

Much of modern physics is based on Albert Einstein's 1905 special theory of relativity – a key piece of which says nothing can travel faster than light in a vacuum. So far, no competing finding or theory has challenged the conclusion.

Scientists say the result could lead to a rethink of one of the most fundamental assumptions of science.


The neutrinos were fired from the CERN facility in Switzerland

"Special relativity is one of the cornerstones of physics," said Johan Bijnens, particle physicist at Lund University in Sweden in an interview with Deutsche Welle. "But if that's not true then we have to really start thinking about how to dissolve it."

At the same time, he strongly warned that that the OPERA results needed to stand up to scrutiny and be independently verified.

"As the saying goes – for sensational results, you need sensational proof," Bijnens said. "So my first reaction is – they must have missed something."

High-precision experiment

The OPERA team behind the experiment, which carried out testing for three years and gathered high-precision data on neutrino movements and how long it exactly took them to make the journey, presented their results in a scientific paper late Thursday. They also planned to detail their findings in a seminar at CERN on Friday.

"One has to be very careful," noted Caren Hagner, a physicist at the University of Hamburg, and a member of the OPERA team, in a Deutsche Welle interview.

Antarctica neutrino experiment

Scientists are working on neutrino experiments all around the globe, including in Antarctica

Hagner said she was amongst some of the most skeptical members of the research group, and advised against releasing OPERA's results to the public at this stage.

"There can be an error in the measure of distance, or the measurement of time, or - because we use statistical methods to disentangle, to measure the time of flight of the neutrinos - it could also result in some nasty statistical effects," she added.

Researchers say replicating an experiment like OPERA is anything but easy, given the expensive, high-precision data involved and the time spans needed to carry out comparative studies.

But Johan Bijnens from the University of Lund pointed out that similar work was currently being done at the Fermilab in the US and in Japan. It will likely fall to them to the MINOS experiment at Fermilab to examine its previously unreleased data on a similar project to see if it matches up with the OPERA finding.

Albert Einstein

Einstein's theories have held up for over a century, and so scientists are hesitant to dismiss them

Understanding neutrinos

Researchers say the experiment could also shed more light on neutrinos, often called ghost particles, because they pass through matter, and human bodies, unnoticed. Neutrinos rarely interact with other matter and are electrically neutral.

"Neutrinos are all around us but they are particles that we actually do not understand very well," Jensen added. "There are actually three kinds of neutrinos. They seem to have some mass – at least some of them – which is not predicted by the standard model theory of particle physics. So any study into them is really interesting."

For now, scientists say it's best to remain wary about the finding that claims to break the speed of light.

"I think before I throw away Einstein, I really think the probability that there is a hidden error is really big," Hagner observed.

Author: Sonia Phalnikar
Editor: Cyrus Farivar

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