
The illustration shows how a Higgs boson may look like in Atlas
Scientists at the CERN research centre near Geneva, Switzerland, will on Wednesday unveil the latest results in
their search for the Higgs boson, a subatomic particle believed to be
key to the formation of stars, planets and eventually life after the Big
Bang 13.7 billion years ago.
WHAT IS THE HIGGS BOSON?
The Higgs is the last missing piece of the Standard Model, the theory
that describes the basic building blocks of the universe. The other 11
particles predicted by the model have been found and finding the Higgs
would validate the model. Ruling it out or finding something more exotic
would force a rethink on how the universe is put together.
Scientists
believe that in the first billionth of a second after the Big Bang, the
universe was a gigantic soup of particles racing around at the speed of
light without any mass to speak of. It was through their interaction
with the Higgs field that they gained mass and eventually formed the
universe.
The
Higgs field is a theoretical and invisible energy field that pervades
the whole cosmos. Some particles, like the photons that make up light,
are not affected by it and therefore have no mass. Others are not so
lucky and find it drags on them as porridge drags on a spoon.
Picture George Clooney
(the particle) walking down a street with a gaggle of photographers
(the Higgs field) clustered around him. An average guy on the same
street (a photon) gets no attention from the paparazzi and gets on with
his day. The Higgs particle is the signature of the field – an eyelash
of one of the photographers.
The particle is theoretical, first posited in 1964 by six physicists, including Briton Peter Higgs.
The search
for it only began in earnest in the 1980s, first in Fermilab’s now
mothballed Tevatron particle collider near Chicago and later in a
similar machine at CERN, but most intensively since 2010 with the
start-up of the European centre’s Large Hadron Collider.
WHAT IS THE STANDARD MODEL?
The Standard Model is to physics what the theory
of evolution is to biology. It is the best explanation physicists have
of how the building blocks of the universe are put together. It
describes 12 fundamental particles, governed by four basic forces.
But the
universe is a big place and the Standard Model only explains a small
part of it. Scientists have spotted a gap between what we can see and
what must be out there. That gap must be filled by something we don’t
fully understand, which they have dubbed ‘dark matter’. Galaxies
are also hurtling away from each other faster than the forces we know
about suggest they should. This gap is filled by ‘dark energy’. This
poorly understood pair are believed to make up a whopping 96 percent of
the mass and energy of the cosmos.
Confirming the Standard Model, or perhaps modifying it, would be a step towards the holy grail of physics – a ‘theory of everything’ that encompasses dark matter, dark energy and the force of gravity,
which the Standard Model also does not explain. It could also shed
light on even more esoteric ideas, such as the possibility of parallel
universes.
CERN
spokesman James Gillies has said that just as Albert Einstein’s theories
enveloped and built on the work of Isaac Newton, the work being done by
the thousands of physicists at CERN has the potential to do the same to
Einstein’s work.
WHAT IS THE LARGE HADRON COLLIDER?
The Large Hadron Collider
is the world’s biggest and most powerful particle accelerator, a 27-km
(17-mile) looped pipe that sits in a tunnel 100 metres underground on
the Swiss/French border. It cost 3 billion euros to build.
Two beams
of protons are fired in opposite directions around it before smashing
into each other to create many millions of particle collisions every
second in a recreation of the conditions a fraction of a second after
the Big Bang, when the Higgs field is believed to have ‘switched on’.
The vast
amount of data produced is examined by banks of computers. Of all the
trillions of collisions, very few are just right for revealing the Higgs
particle. That makes the hunt for the Higgs slow, and progress incremental.
WHAT IS THE THRESHOLD FOR PROOF?
To claim a
discovery, scientists have set themselves a target for certainty that
they call “5 sigma”. This means that there is a probability of less than
one in a million that their conclusions from the data harvested from the particle accelerator are the result of a statistical fluke.
The two teams hunting for the Higgs at CERN, called Atlas
and CMS, now have twice the amount of data that allowed them to claim
‘tantalising glimpses’ of the Higgs at the end of last year and this
could push their results beyond that threshold.
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