Einstein’s laws questioned as speed of light is broken again
by Steve Connor
An experiment showing it is possible to travel faster than the speed
of light, and so confound a fundamental principle of theoretical
physics, has passed its first serious test of validity.
Scientists have excluded one of the sources of error that could have
led them to make a mistake when they announced in September that a beam
of sub-atomic particles had travelled a fraction of a second faster than
light.
They repeated the first experiment, in which they had fired pulses of
neutrons from the Cern underground laboratory near Geneva through solid
rock to subterranean particle detectors at the Gran Sasso National
Laboratory in Italy about 750km (466 miles) away.
This time the length of the neutron pulses was shortened to eliminate
one possible source of error.
Instead of the pulses lasting 10.5 millionths of a second, as in the
original experiment, they were made about 3,000 times shorter, at just 3
billionths of a second.This enabled experimenters to eliminate the
possibility that they were getting confused over the start and end of
each pulse – critical with measurements involving minute fractions of a
second.
Like the earlier experiment, the test found the neutrons arrived at
the Italian site some 60 billionths of a second faster than if they were
travelling at light speed – some 186,282 miles per second and supposedly
the maximum velocity at which anything can move.
Travelling faster than light is considered impossible under the
current laws of physics. Breaking the universal constant would overturn
Albert Einstein’s special theory of relativity, which has held sway over
theoretical physics for more than a century.
“A measurement so delicate and carrying a profound implication on
physics requires an extraordinary level of scrutiny,” said Professor
Fernando Ferroni, president of the Italian Institute for Nuclear Physics
and a spokesman for the international Opera consortium, which carried
out the test.
“The positive outcome of the test makes us more confident of its
result, although a final word can only be said by analogous measurements
performed elsewhere in the world. One of the eventual systematic errors
is now out of the way, but the search is not over.”
Physicists now await a repeat of the experiment by other researchers
at the Minos group at Fermilab in Batavia, Illinois, before they tear up
their textbooks – or eat their boxer shorts, as Prof Jim Al-Khalili at
Surrey University vowed to do if the experiment proved correct.
“I am not yet ready to get out my knife and fork,” he said. “The
results have only dealt with some possible errors. There are still a
number of other possible errors and uncertainties that they are working
on ruling out.
“Ideally, the experiment would have to be done somewhere else
entirely to try to verify the controversial result that these tiny
particles really are going faster than light in case there is still a
systemic problem with this particular experiment at Cern.”
In numbers
299,792,458
The speed of light, in metres per second – a universal constant in
the laws of physics
730
Distance travelled (in km), by neutrinos in Cern experiment
60
Billionths of a second – how much faster than light the neutrinos
travelled
The Cern results appear to overturn Einstein’s theory of relativity.
- PA
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