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GENEVA – Why is the Higgs boson - posited by an atheistic physicist nearly 50 years ago - called the 'God particle'? The answer is as simple as it is profound.
The Higgs has been dubbed the "God particle" because scientists say it is powerful and everywhere – critical to conferring mass on everything in the known universe, and to keeping the same together - and yet it has been so hard to find.
Peter Higgs, the now 83-year-old physicist who first theorized the boson's existence 48 years ago, actually frowns upon the term. A modest man, Higgs is said to have cringed every time the term "Higgs boson" was used in his presence and studiously avoided using it. But as a self-proclaimed atheist, Higgs disliked the boson's other name, "God particle", even more.
Whatever people prefer to call it, after a quest spanning nearly half a century, physicists said Wednesday they had found a sub-atomic particle that may be the elusive Higgs boson, believed to confer mass on matter.
Finding the Higgs would validate the Standard Model, a theory which identifies the building blocks for matter and the particles that convey fundamental forces.
The Standard Model is a hugely successful theory but has several gaps, the biggest of which is why some particles have mass but others do not.
Mooted by Higgs and several others, the boson is believed to exist in a treacly, invisible, ubiquitous field created by the Big Bang some 13.7 billion years ago.
When some particles encounter the Higgs, they slow down and acquire mass, according to the theory. Others, such as particles of light, encounter no obstacle.
Over the years, tens of thousands of physicists and billions of dollars have been thrown into the search, gradually narrowing down the mass range where it might exist.
Two CERN laboratories, working independently of each other to avoid bias, found the new particle in the mass region of around 125-126 Gigaelectronvolts (GeV), according to data they presented on Wednesday.
Both said that the results were "five sigma," meaning there was just a 0.00006 percent chance that what the two laboratories found is a mathematical quirk.
"The results are preliminary but the five sigma signal at around 125 GeV we're seeing is dramatic," said Joe Incandela, spokesman for one of the two experiments.
"This is an important result and should earn Peter Higgs the Nobel Prize, but it is a pity in a way, because the great advances in physics have come from experiments that gave results we didn't expect," said cosmologist Stephen Hawking in an interview with the BBC.
"For this reason I had a bet with Gordon Kane of Michigan University that the Higgs particle wouldn't be found. It seems I have just lost $100."
CERN physicist Yves Sirois said that the result did seem to back the Standard Model but further surprises could be in store.
"It may be the Higgs boson, but it may also be something far bigger, which opens the door towards a new theory that goes beyond the Standard Model."
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 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 infographic below, from the website of LiveScience.com, has another celebrity-centered analogy to illustrate how the Higgs particle is essential to the very concept of mass in physics. Click on the image to view a larger version in a separate window.
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.
In the video below, Fermilab scientist Don Lincoln uses the concept of water to expound on how the Higgs particle and the Higgs field is essential to everything that surrounds us.
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 of 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.
Agence France-Presse | InterAksyon.com, with material from LiveScience.com and Fermilab