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from: The Higgs boson made simple – http://cosmiclog.msnbc.msn.com
So what’s the Higgs boson, and why are people spending billions of dollars to find that god-danged subatomic particle? I’ve rounded up a variety of resources aimed at showing you why the hunt for the Higgs is a big deal.
First, a little context: The Higgs particle, and its associated field, were hypothesized back in the 1960s by British physicist Peter Higgs and others to fill a weird gap in the Standard Model, one of physics’ most successful theories. The model as it stood had no mechanism to explain why some particles are massless (such as the photon, which is the quantum bit for light and other types of electromagnetic radiation), while other particles have varying degrees of mass (such as the W and Z bosons, which play a part in the weak nuclear force). By rights, all particles should be without mass and zipping around freely.
The Higgs mechanism sets up a field that interacts with particles to endow them with mass, and the Higgs boson is the particle associated with that field — just as photons are associated with an electromagnetic field. For more than four decades, physicists have assumed that the Higgs field existed, but found no experimental evidence for it. It requires a super-powerful particle smasher such as the Large Hadron Collider to produce energies high enough to knock a Higgs boson into existence under controlled conditions.
But the heavy particles created in a collider exist for just an instant before they decay into lighter particles. The LHC’s physicists have been looking for particular patterns in the spray of particles that match what they’d expect to see from the decay of the Higgs boson. They’ve collected data for roughly a quadrillion proton-on-proton collisions, and on Wednesday they’ll announce the status of the Higgs search based on those conclusions. (read: Higgs boson: scientists 99.999% sure ‘God Particle’ has been found)
The teams at the LHC’s ATLAS and CMS detectors are likely to say they’re pretty sure they see a new type of particle with Higgs-like characteristics, but will need more time to nail down those characteristics completely. If that’s the case, physicists can then go on to find out if the Higgs mechanism works exactly the way they expected it to, or whether there are unexpected twists. Some of the theories about how the universe is put together are pretty far-out — for example, suggesting that there are several dimensions in space that we can’t perceive directly, or that there are huge troops of subatomic particles that we haven’t yet discovered. Following the tracks left behind by the Higgs could reveal whether there’s any truth to those theories.
For decades, experts have been trying to come up with analogies to illustrate how the Higgs mechanism works. One of the best-known was proposed in 1993 by David Miller, a physicist at University College London. Imagine looking down from a balcony in a ballroom, watching a cocktail party below. When just plain folks try to go from one end of the room to the other, they can walk through easily, with no resistance from the party crowd. But when a celebrity like Justin Bieber shows up, other partygoers press around him so tightly that he can hardly move … and once he moves, the crowd moves with him in such a way that the whole group is harder to stop.
The partygoers are like Higgs bosons, the just plain folks are like massless particles, and Bieber is like a massive Z boson.
The Guardian’s Ian Sample demonstrates a variant of this analogy in a 4.5-minute video: Imagine a tray with ping-pong balls scattered on it. The balls roll freely around the empty tray. But then, if you spread a layer of sugar over the tray, the balls sitting on the piled-up sugar don’t roll so easily. The grains of sugar introduce a kind of inertial “drag,” and that’s the kind of effect that the Higgs field supposedly has on particles with mass.
In a 60-second shot of science written for Symmetry magazine, Howard Haber of the University of California at Santa Cruz uses a livelier comparison to a high-speed bullet plowing through a vat of molasses.
What good is it?
Particle physicists try to avoid forecasting the applications of an experimental advance before the actual advance is confirmed, but in the past, advances on a par with the discovery of the Higgs boson have had lots of beneficial applications, and some that are more questionable. The rise of nuclear power and nuclear weaponry is a prime example of that double-edged sword.
Scientists believe they have captured the elusive “God particle” that gives matter mass and holds the physical fabric of the universe together.
Professor John Womersley. chief executive of the Science and technology Facilities Council, told reporters at a briefing in London: “They have discovered a particle consistent with the Higgs boson.
“Discovery is the important word. That is confirmed. It’s a momentous day for science.”
Scientists say it is a 5 sigma result which means they are 99.999% sure they have found a new particle.
Finding the Higgs plugs a gaping hole in the Standard Model, the theory that describes all the particles, forces and interactions that make up the universe.
If the particle was shown not to exist, it would have meant tearing up the Standard Model and going back to the drawing board.
The Cern laboratory appeared to have let slip its biggest breakthrough in a generation after appearing to announce the discovery of a new particle in an online video overnight.
In the short film accidentally published by the lab yesterday spokesman Joe Incandela is seen describing how physicists at the Large Hadron Collider had “observed a new particle”.
Today scientists gathered in Geneva to announce the findings. Among the audience was Peter Higgs, the Edinburgh professor who first proposed the existence of the mysterious particle almost 50 years ago.
Rumours had been rife that scientists hunting the Higgs were to announce today’s finding but the video appeared to confirm the finding of a particle matching its description hours before it was confirmed.
Although their results are said to be strong enough to claim an official discovery, the scientists will avoid doing so because they remain unsure whether the particle they have found is indeed the Higgs.
Cern spokesman James Gillies said the video was one of several filmed to cover every eventuality and did not directly relate to today’s announcement.
The Internet has been rife with rumours of a discovery ever since CERN, the European nuclear research facility, announced it would hold a press conference today with the leaders of its two gigantic experiments, ATLAS and CMS.
Sources have told the Telegraph that ATLAS will today announce a 5-sigma signal and CMS will announce a 4.9-sigma signal of a new particle with a mass of 126.5 GigaelectronVolts (GeV) and 125.2 GeV respectively – a result which falls slap bang in the middle of the tough-to-explore region where many physicists were adamant the Higgs was hiding.
The results being announced today definitively point to a new particle or particles which fit the description of a Higgs Boson, but further research will be needed to characterise it properly.
The Higgs boson is the final piece of the Standard Model of Particle Physics, a theoretical model which describes the fundamental particles and forces that control our Universe.
It was first theorised in the 1960s by Edinburgh-based physicist Peter Higgs, amongst others, and is credited for giving all other particles mass. But until now, it has proved impossible to pin down.
To do so, scientists use the LHC to smash together protons at almost the speed of light and scour the debris for traces of particles that sprang into existence for just a fraction of a second before disintegrating.
Sources have told the Telegraph that ATLAS will today announce a 5-sigma signal and CMS will announce a 4.9-sigma signal of a new particle with a mass which matches many physicists’ idea of a Higgs Boson.
An ATLAS researcher said there was “no question” the two detectors are seeing the same thing, adding: “A lot of bets are going to be settled up [today]”.
“After so many years preparing and searching, it’s really amazing to see a clear signal emerge,” a CMS Higgs physicist added.
“This is the sort of thing that makes me cry,” said an ATLAS Higgs physicist. “It’s the kind of crying that accompanies winning something or being overwhelmed with happiness. Human thought and ingenuity have continually created and discovered, but this outdoes them all.”