guardian.co.uk,
Ian Sample, science correspondent, Thursday 22 September 2011
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| Neutrinos, like the ones above, have been detected travelling faster than light, say particle physicists. Photograph: Dan Mccoy /Corbis |
It is a
concept that forms a cornerstone of our understanding of the universe and the
concept of time – nothing can travel faster than the speed of light.
But now it
seems that researchers working in one of the world's largest physics
laboratories, under a mountain in central Italy, have recorded particles
travelling at a speed that is supposedly forbidden by Einstein's theory of
special relativity.
Scientists
at the Gran Sasso facility will unveil evidence on Friday that raises the
troubling possibility of a way to send information back in time, blurring the
line between past and present and wreaking havoc with the fundamental principle
of cause and effect.
They will
announce the result at a special seminar at Cern – the European particle physics laboratory – timed to coincide with the publication of a research paper
(pdf) describing the experiment.
Researchers
on the Opera (Oscillation Project with Emulsion-tRacking Apparatus) experiment
recorded the arrival times of ghostly subatomic particles called neutrinos sent
from Cern on a 730km journey through the Earth to the Gran Sasso lab.
The trip
would take a beam of light 2.4 milliseconds to complete, but after running the
experiment for three years and timing the arrival of 15,000 neutrinos, the
scientists discovered that the particles arrived at Gran Sasso sixty billionths
of a second earlier, with an error margin of plus or minus 10 billionths of a
second.
The
measurement amounts to the neutrinos travelling faster than the speed of light
by a fraction of 20 parts per million. Since the speed of light is 299,792,458
metres per second, the neutrinos were evidently travelling at 299,798,454
metres per second.
The result
is so unlikely that even the research team is being cautious with its
interpretation. Physicists said they would be sceptical of the finding until
other laboratories confirmed the result.
Antonio
Ereditato, coordinator of the Opera collaboration, told the Guardian: "We
are very much astonished by this result, but a result is never a discovery
until other people confirm it.
"When
you get such a result you want to make sure you made no mistakes, that there
are no nasty things going on you didn't think of. We spent months and months
doing checks and we have not been able to find any errors.
"If
there is a problem, it must be a tough, nasty effect, because trivial things we
are clever enough to rule out."
The Opera
group said it hoped the physics community would scrutinise the result and help
uncover any flaws in the measurement, or verify it with their own experiments.
Subir
Sarkar, head of particle theory at Oxford University, said: "If this is
proved to be true it would be a massive, massive event. It is something nobody
was expecting.
"The
constancy of the speed of light essentially underpins our understanding of
space and time and causality, which is the fact that cause comes before effect.
"Cause
cannot come after effect and that is absolutely fundamental to our construction
of the physical universe. If we do not have causality, we are buggered."
The Opera
experiment detects neutrinos as they strike 150,000 "bricks" of
photographic emulsion films interleaved with lead plates. The detector weighs a
total of 1300 tonnes.
Despite the
marginal increase on the speed of light observed by Ereditato's team, the
result is intriguing because its statistical significance, the measure by which
particle physics discoveries stand and fall, is so strong.
Physicists
can claim a discovery if the chances of their result being a fluke of
statistics are greater than five standard deviations, or less than one in a few
million. The Gran Sasso team's result is six standard deviations.
Ereditato
said the team would not claim a discovery because the result was so radical.
"Whenever you touch something so fundamental, you have to be much more
prudent," he said.
Alan
Kostelecky, an expert in the possibility of faster-than-light processes at
Indiana University, said that while physicists would await confirmation of the
result, it was none the less exciting.
"It's
such a dramatic result it would be difficult to accept without others
replicating it, but there will be enormous interest in this," he told the
Guardian.
One theory
Kostelecky and his colleagues put forward in 1985 predicted that neutrinos
could travel faster than the speed of light by interacting with an unknown
field that lurks in the vacuum.
"With
this kind of background, it is not necessarily the case that the limiting speed
in nature is the speed of light," he said. "It might actually be the
speed of neutrinos and light goes more slowly."
Neutrinos
are mysterious particles. They have a minuscule mass, no electric charge, and
pass through almost any material as though it was not there.
Kostelecky
said that if the result was verified – a big if – it might pave the way to a
grand theory that marries gravity with quantum mechanics, a puzzle that has
defied physicists for nearly a century.
"If
this is confirmed, this is the first evidence for a crack in the structure of
physics as we know it that could provide a clue to constructing such a unified
theory," Kostelecky said.
Heinrich
Paes, a physicist at Dortmund University, has developed another theory that
could explain the result. The neutrinos may be taking a shortcut through
space-time, by travelling from Cern to Gran Sasso through extra dimensions.
"That can make it look like a particle has gone faster than the speed of
light when it hasn't," he said.
But Susan
Cartwright, senior lecturer in particle astrophysics at Sheffield University,
said: "Neutrino experimental results are not historically all that
reliable, so the words 'don't hold your breath' do spring to mind when you hear
very counter-intuitive results like this."
Teams at
two experiments known as T2K in Japan and MINOS near Chicago in the US will now
attempt to replicate the finding. The MINOS experiment saw hints of neutrinos
moving at faster than the speed of light in 2007 but has yet to confirm them.
"The Quantum Factor Physics with an attitude" – Apr 10, 2011 (Kryon channeled by Lee Carroll) (Subjects: Galaxies, Universe, Intelligent design, Benevolent design, Aliens, Nikola Tesla (Quantum energy), Inter-Planetary Travel, DNA, Genes, Stem Cells, Cells, Rejuvenation, Shift of Human Consciousness, Spontaneous Remission, Religion, Dictators, Africa, China, Nuclear Power, Sustainable Development, Animals, Global Unity.. etc.)
"Energetics Conciousness" – Jul 17, 2010 (Kryon channeled by Lee Carroll) (Subjects: DNA, Galaxies, Universe, Intelligent design, Multidimensional, Talking to the Dead: Different Than You Think, Time is Complex, Global Unity.. etc.)
(.... I want to
show you how time works, but I can't. It's because the reality of the
complexities of multidimensionality preclude the Human Being's ability to
understand it. It's simply not teachable in your 3D perception. So I will
metaphorize it and give it to you in its simplest form, which is only a
fraction of its reality. ...)
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