Scientists said on Thursday they recorded particles
travelling faster than light – a finding that could overturn one of Einstein’s
fundamental laws of the universe. Antonio Ereditato, spokesman for the
international group of researchers, saidthat measurements taken over three
years showed neutrinos pumped from CERN near Geneva to Gran Sasso in Italy had
arrived 60 nanoseconds quicker than light would have done.
“We have high confidence in our results. We have
checked and rechecked for anything that could have distorted our measurements
but we found nothing,” he said. “We now want colleagues to check them
independently.”
If confirmed, the discovery would undermine Albert
Einstein’s 1905 theory of special relativity, which says that the speed of
light is a “cosmic constant” and that nothing in the universe can travel
faster. That assertion, which has withstood over a century of testing, is one
of the key elements of the so-called Standard Model of physics, which attempts
to describe the way the universe and everything in it works. The totally
unexpected finding emerged from research by a physicists working on an
experiment dubbed OPERA run jointly by the CERN particle research center near
Geneva and the Gran Sasso Laboratory in central Italy.
A total of 15,000 beams of neutrinos – tiny
particles that pervade the cosmos – were fired over a period of three years
from CERN towards Gran Sasso 730 (500 miles) km away, where they were picked up
by giant detectors. Light would have covered the distance in around 2.4
thousandths of a second, but the neutrinos took 60 nanoseconds – or 60
billionths of a second – less than light beams would have taken.
“It is a tiny difference,” said Ereditato, who also
works at Berne University in Switzerland, “but conceptually it is incredibly
important. The finding is so startling that, for the moment, everybody should
be very prudent.”
Ereditato declined to speculate on what it might
mean if other physicists, who will be officially informed of the discovery at a
meeting in CERN on Friday, found that OPERA’s measurements were correct.
“I just don’t want to think of the implications,” he
said. “We are scientists and work with what we know.”
Much science-fiction literature is based on the idea
that, if the light-speed barrier can be overcome, time travel might
theoretically become possible. The existence of the neutrino, an elementary
sub-atomic particle with a tiny amount of mass created in radioactive decay or
in nuclear reactions such as those in the Sun, was first confirmed in 1934, but
it still mystifies researchers.
It can pass through most matter undetected, even
over long distances, and without being affected. Millions pass through the
human body every day, scientists say. To reach Gran Sasso, the neutrinos pushed
out from a special installation at CERN – also home to the Large Hadron
Collider probing the origins of the universe – have to pass through water, air
and rock.
The underground Italian laboratory, some 120 km (75
miles) to the south of Rome, is the largest of its type in the world for
particle physics and cosmic research. Around 750 scientists from 22 different
countries work there, attracted by the possibility of staging experiments in
its three massive halls, protected from cosmic rays by some 1,400 meters (4,200
feet) of rock overhead.
What has happened at CERN?
Scientists say they have clocked neutrinos – tiny
particles smaller than atoms – travelling at 300,006 kilometers per second,
slightly faster than the speed of light.
What does that mean?
Einstein’s theory of special relativity says nothing
can travel faster than the speed of light in a vacuum, because photons – light
particles – have no mass. Proof that neutrinos, mysterious subatomic particles
which have a tiny amount of mass, can travel faster would be inconsistent with
Einstein’s theory.
What are the knock-on effects?
Einstein’s theory is critical to the Standard Model
of physics that helps explain everything we know about how the universe works,
from black holes to the big bang. If it is shown to be flawed, virtually
everything in modern physics and the fundamental laws of nature would have to
be rethought.
Have the results been proven? The findings were such
a shock that CERN’s scientists spent months checking their data before making
their announcement. But they have asked American and Japanese teams to confirm
the results before they are declared an actual discovery. The data will also be
put online overnight so that it can be scrutinized by experts across the world.
Does this mean E does not equal MC squared? The
theory of special relativity was used to spawn the theory that energy is equal
to mass multiplied by the speed of light squared. It is premature to discount
the most famous equation of all time, but the latest discovery suggests one key
assumption it relies on – that nothing can accelerate faster than light – may
not be wholly accurate.
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