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06 Jul 2012 06:57
All about the Higgs: a presentation at the Australian Science Media Centre. (Mal Fairclough, Reuters)
The discovery – or probable discovery – at Cern, the particle physics lab near Geneva, will go down as a triumph of science, engineering and collective hard graft. Now the real work begins.
Years of analysis lie ahead to confirm that the particle is the elusive Higgs boson.
If so, physicists want to know whether it is the simplest kind of particle put forward in physicists’ theories, or something more unusual – and more exciting.
“It’s clear there’s a great deal more to be done experimentally, even after they announce a discovery,” said Steven Weinberg, a professor of physics at the University of Texas in Austin, who won the Nobel Prize in 1979 for work that used the mathematics behind the Higgs theory to show how two forces of nature, the electromagnetic force that carries light and the weak force that drives some kinds of radioactive decay, were one in the early universe.
Finding the particle proves there is an energy field that fills the vacuum of the observable universe.
The Higgs field is thought to have switched on a trillionth of a second after the big bang that blasted the universe into existence. Without it, or something to do its job, the structure of the cosmos would be radically different to what it is today.
Something more complex?
The tough job ahead is working out whether the Higgs particle is the simple, singular particle that underpins what physicists call the standard model – equations that describe how all the known particles behave – or something more complex.
One possibility is that the particle is one of a larger family of Higgs particles. To find out they must study how the particle is made in the large hadron collider and how it disintegrates into other, more familiar particles as soon as it is created.
“It will take a lot of time. I don’t mean decades, but perhaps years to verify all the predictions of the standard model about how the particle is produced and how it decays,” Weinberg said.
The race at Cern now is to collect as much information about the particle as possible before the collider closes down for about two years at the end of 2012 to allow engineers to carry out repairs that will enable it to run at its full design energy.
Much is riding on what Cern finds, or fails to find. Some physicists fear the laboratory might discover only the simplest form of Higgs particle and nothing more exotic. That would plug a hole in the standard model, but give scientists no leads to help them understand other pressing mysteries in nature.
“I had a nightmare, which is that Cern would discover the Higgs boson and then nothing else … gratifying as it is, [it] does not provide a clue to how to go beyond the standard model,” Weinberg said. So far the collider has not revealed anything unexpected. “I find it a very depressing prospect, the possibility that this may be the last great discovery for many decades,” he said. – © Guardian News & Media 2012
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