|Exploring the Deepest Fabric of the Universe|
Scientists at CERN now believe that they've seen the Higgs. Not with their own eyes, but with massive computer systems hitched up to the Large Hadron Collider, a circular tube 16.8 miles (27 kilometers) in circumference that accelerates raw protons and other particles in opposite directions around the ring 11,000 times per second. At the perfect moment, they slam into each other, producing a massive explosion thought to rival the Big Bang, except on a much smaller scale. Only a particle collider can produce that much energy—the amount needed to produce a viewable Higgs.
Physicist are closer than ever to proving the existence of the elusive subatomic Higgs boson - often called the "God particle" because it may bring mass and order to the universe. Joe Incandela, spokesperson for the CMS experiment, which represetnts 183 scientific institutes and 38 countries, confirms that they have found a new particle but stops short of calling it the Higgs. "We've observed a new particle and there is strong evidence there's something there".
An undated image made available by CERN (see below) shows a typical candidate event including two high-energy photons whose energy (depicted by red towers) is measured in the CMS electromagnetic calorimeter. The yellow lines are the measured tracks of other particles produced in the collision. The pale blue volume shows the CMS crystal calorimeter barrel. To cheers and standing ovations, scientists at the world's biggest atom smasher claimed the discovery of a new subatomic particle Wednesday July 4, 2012, calling it "consistent" with the long-sought Higgs boson — popularly known as the "God particle" — that helps explain what gives all matter in the universe size and shape.
He also calls it "one of the biggest discoveries in our field in the last 30 to 40 years", adding: "the significance of this observation could be very very great." We don't yet know whether this particle is consistent with the standard-model Higgs, or if it doesn't exactly match up. "If that's the case, then we have something really quite profound here," says Inca
ndela. "It could be a gateway, if you like, to the next phase of exploring the deepest fabric of the universe, which is pretty profound when you think about it." These results are still preliminary, however. Incandela compares the amount of data recorded to the number of grains of sand that would fill an Olympic swimming pool, while only "tens, or dozens" represent the observations that could be the Higgs. "We've just got enough data to say it's definitely there and it's very unlikely to go away." There is still the possibility this observation is not the Higgs, however. "It may be something which we often call a Higgs-like particle," says Incandela. "If it doesn't match in a significant way then we may be able to find that out this year."
Finding the Higgs was a key goal for the $10bn (£6bn) Large Hadron Collider (LHC) - a 27km (17-mile) circumference accelerator ring of superconducting magnets, designed to re-create the conditions just after the Big Bang in an attempt to answer fundamental questions of science and the Universe itself. The collider hosts two experiments - Atlas and CMS - that are searching for the particle independently. There is intense excitement among physicists working at Cern, the Geneva-based organisation which operates the collider, over hints that the hunters have cornered their quarry. "It is a fantastic time at the moment, you can feel people are enthusiastic," Dr Christoph Rembser, a senior scientist on the Atlas experiment, explained: "It is really very lively." "Start Quote If the Universe really is like that, I find it really quite breathtaking and humbling that we can understand it." Prof Soldner-Rembold called the quality of the LHC's results "exceptional", adding: "The Higgs particle would, of course, be a great discovery, but it would be an even greater discovery if it didn't exist where theory predicts it to be." The Higgs boson is a "fundamental" particle; one of the basic building blocks of the Universe. It is also the last missing piece in the leading theory of particle physics - known as the Standard Model - which describes how particles and forces interact.
The Higgs explains why other particles have mass. As the Universe cooled after the Big Bang, an invisible force known as the Higgs field formed together with its associated boson particle. It is this field (and not the boson) that imparts mass to the fundamental particles that make up atoms. Without it, these particles would zip through the cosmos at the speed of light. It comes as the search for the mysterious fundamental particle reaches its endgame. If so, this will be a significant milestone for teams at the famous Large Hadron Collider (LHC). The particle-accelerating machine on the French-Swiss border was built with the hunt for the Higgs as a key goal. The collider smashes beams of protons together in head-on collisions, with signs of the Higgs boson, perhaps, in the debris.
The Higgs boson is notoriously difficult to define, but its existence helps us to understand why particles have mass. The search for the Higgs has become the hottest pursuit in modern physics. It is separate from the unexpected announcement in September of the apparently faster-than-light neutrinos, a result which is still puzzling the world of physics, and has taken the limelight recently. This year alone they've searched the remains of some 350 trillion collisions, with only ten or so producing candidates for a reliable sign of the Higgs. Professor John Ellis: "We've been living with Higgs theory now for almost 50 years... it's become our Holy Grail." There are two teams of scientists working independently, using two separate detectors - called ATLAS and CMS - each relying on different technologies. This way they provide an independent cross-check for each other. How closely their results agree will be an important measure of how significant a finding they can claim. The teams are sworn to secrecy, but various physics blogs, and the canteens at Cern, are alive with talk of a possible sighting of the Higgs, and with a mass inline with what many physicists would expect. The teams have been focussing-in on the Higgs by ruling out energy ranges where it might be lurking. They now expect to see it at around 120 to 125 GeV (gigelectronvolts), where one GeV is about the mass of a proton. "I think with the recent discovery we are going to get the first glimpse. The LHC experiments have already looked high and low for this missing piece. It could be that it weighs several hundred times the proton mass, but that seems very unlikely, then there's a whole intermediate range where we know it cannot be, then there's the low mass range where we actually expect it might be. Professor Ellis, who is now a guest professor at Cern, and was recently made James Clerk Maxwell professor at King's College, London, feels that finding the Higgs matters hugely to modern physics. "What we have at the moment is something we call the Standard Model, that describes all fundamental particle physics. You can think of it as being an enormous giant Jigsaw puzzle, but there's a piece missing right in the middle there. We have been looking for this for 30 years now, and finally, maybe, hidden under the back of the LHC sofa...we are finally finding it". Understandably perhaps, the director of research at Cern, Sergio Bertolucci, is being more cautious than Professor Ellis. He told me, somewhat enigmatically: "It's too early to say...I think we may get indications that are not consistent with its non-existence." He expects the current results to amount to less than the formal definition of "evidence", but said the statistics will be "very interesting". "I would be very inclined to say just that we will not give anything except an update which will tell people we are on a good path to the discovery." Scientist believe that the hunt for the Higgs is like fishing in an ancient way, where instead of using modern tools you are removing the water from the pond. It might look tedious but it is the only way, at the end of the day, when you have removed all the water from the pond to find the smallest fish.
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