GENEVA (Reuters) - Scientists at Europe's CERN research centre have found a new subatomic particle,
a basic building block of the universe, which appears to be the boson
imagined and named half a century ago by theoretical physicist Peter Higgs.
"We have reached a
milestone in our understanding of nature," CERN director general Rolf
Heuer told a gathering of scientists and the world's media near Geneva
on Wednesday.
"The discovery of a particle consistent with the Higgs boson
opens the way to more detailed studies, requiring larger statistics,
which will pin down the new particle's properties, and is likely to shed
light on other mysteries of our universe."
Two independent
studies of data produced by smashing proton particles together at CERN's
Large Hadron Collider produced a convergent near-certainty on the
existence of the new particle.
It is unclear that
it is exactly the boson Higgs foresaw, which by bestowing mass on other
matter helps explain the way the universe was ordered after the chaos of
Big Bang.
But addressing
scientists assembled in the CERN auditorium, Heuer posed them a
question: "As a layman, I would say I think we have it. Would you
agree?" A roar of applause said they did.
For some, there was
no doubt the Higgs boson is found: "It's the Higgs," said Jim
Al-Khalili of Surrey University, a British physicist and popular
broadcaster. "The announcement from CERN is even more definitive and
clear-cut than most of us expected.
"Nobel prizes all round."
Higgs, now 83, from
Edinburgh University was among six theorists who in the early 1960s
proposed the existence of a mechanism by which matter in the universe
gained mass. Higgs himself argued that if there were an invisible field
responsible for the process, it must be made up of particles.
He and some of the
others were at CERN to welcome news of what, to the embarrassment of
many scientists, some commentators have labelled the "God particle", for
its role in turning the Big Bang into an ordered universe. Clearly
overwhelmed, his eyes welling up, Higgs told the symposium of fellow
researchers: "It is an incredible thing that it has happened in my
lifetime."
Scientists see
confirmation of his theory as accelerating investigations into the still
unexplained "dark matter" they believe pervades the universe and into
the possibility of a fourth or more dimensions, or of parallel
universes. It may help in resolving contradictions between their model
of how the world works at the subatomic level and Einstein's theory of
gravity.
END OF AN ERA
"It is very satisfying," Higgs told Reuters. "For me
personally it's just the confirmation of something I did 48 years ago,"
he said of the achievement of the thousands who laboured on the
practical experimental work which had, finally, confirmed what he and
others had described with mathematics.
"I had no
expectation that I would still be alive when it happened," he said of
the speed with which they found evidence.
"For physics, in
one way, it is the end of an era in that it completes the Standard
Model," he said of the basic theory physicists currently use to describe
what they understand so far of a cosmos built from 12 fundamental
particles and four forces.
CERN's Large Hadron Collider is the world's biggest and most powerful particle accelerator.
Two beams of protons are fired in opposite directions around the 27-km
(17-mile) looped pipe built under the Swiss-French border before
smashing into each other.
The collisions,
which mimic the moments just after the Big Bang, throw off debris
signals picked up by a vast complex of detectors and the data is
examined by banks of computers.
The two separate
CERN teams worked independently through that data, hunting for tiny
divergences which might betray the existence of the new boson, a class
of particle that includes the photon, associated with light. The class
is named in honour of Albert Einstein's Indian collaborator Satyendra
Nath Bose.
Both teams found strong signals of the new particle at
around 125 to 126 gigaelectron volts (GeV) - a unit of mass-energy. That
makes it some 130-140 times heavier than a proton.
Scientists
struggling to explain the theory have likened Higgs particles to a
throng of paparazzi photographers; the greater the "celebrity" of a
passing particle, the more the Higgs bosons get in its way and slow it
down, imparting it mass; but a particle such as a photon of light is of
no interest to the paparazzi and passes through easily - a photon has no
mass.
Presenting the
results, Joe Incandela at CERN showed off two peaks on a graph of debris
hitting the detectors, which he said revealed the hitherto unseen
presence of the enigmatic particle. "That is what we are sure is the
Higgs," a CERN scientist said.
LESS THAN ONE IN A MILLION"It's a boson!" headlined Britain's Science and Technology Facilities Council in a statement on the role its researchers had played in the delivery of the "dramatic 5 sigma signal" for the existence of the long-sought particle.
Five sigma, a
measure of probability reflecting a less than one in a million chance of
a fluke in the data, is a widely accepted standard for scientists to
agree the particle exists.
"The fact that both
our teams have independently come to the same results is very
powerful," Oliver Buchmueller, a senior physicist on one of the research
teams, told Reuters.
"We know it is a new boson. But we still have to prove definitively that it is the one that Higgs predicted."
"If I were a
betting man, I would bet that it is the Higgs. But we can't say that
definitely yet. It is very much a smoking duck that walks and quacks
like the Higgs. But we now have to open it up and look inside before we
can say that it is indeed the Higgs."
Al-Khalili said the researchers' caution was extreme:
"Cutting through all the jargon about sigmas and decay channels, the
bottom line is that CERN have indeed discovered the Higgs boson," he
said. "In my view, if it looks like the Higgs, smells like the Higgs and
is exactly what we expected from the Higgs, then it's the Higgs."UNIVERSAL THEORY
The Higgs theory
explains how particles clumped together to form stars, planets and life
itself. Without the Higgs boson, the universe would have remained a
formless soup of particles shooting around at the speed of light, the
theory goes.
It is the last
undiscovered piece of the Standard Model that describes the fundamental
make-up of the universe. The model is for physicists what the theory of
evolution is for biologists.
What scientists do
not yet know from the latest findings is whether the particle they have
discovered is the Higgs boson as exactly described by the Standard
Model. It could be a variant of the Higgs idea or an entirely new
subatomic particle that could force a rethink on the fundamental
structure of matter.
The last two possibilities are, in scientific terms, even more exciting.
Packed audiences of
particle physicists, journalists, students and even politicians filled
conference rooms in Geneva, London and a major physics conference in
Melbourne, Australia, to hear the announcement.
Despite the
excitement, physicists cautioned that there was still much to learn: "We
have closed one chapter and opened another," said Peter Knight of
Britain's Institute of Physics.
Paul Nurse,
president of Britain's science academy The Royal Society, said: "This is
a big day for science and for human achievement ... Today moves us a
step closer to a fuller understanding of the very stuff of which the
universe is made."
Higgs himself
called it a great achievement for CERN's collider. Without it, his ideas
would remain just a paper theory and he conceded that he personally was
never cut out for laboratory experimentation: "I certainly did some lab
work as a schoolboy in Bristol," he told Reuters. "I was incompetent."
(Additional reporting by Rosalba O'Brien in London and Sonali Paul in
Melbourne; Writing by Alastair Macdonald)
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