The search for the ‘God Particle’
It is called ATLAS, after the Greek god who carried the weight of the world on his shoulders. One hundred fifty feet long, 82 feet high and weighing 7,000 tons, this mammoth machine has been designed to measure particles so small you can fit hundreds of billions of them into a beam less than a human hair in width.For the next few months, Ph.D. students, professors and Nobel Prize-winners will hurry around it like Lilliputians tending to a giant. Between now and its startup, every pipe, magnet and sensor will be tested and tested again.Then the machine will be switched on, and the world will hold its breath. The search for the “God Particle” will have begun.At stake are some of physics’ deepest problems: Why is there mass in the universe? What is dark matter? Why is the universe expanding at an alarming rate?Located at the CERN laboratory outside Geneva, the world’s largest particle accelerator has taken 25 years to plan and nearly $6 billion to build.When it is switched on, two beams of proton particles will travel in opposite directions around a 17-mile ring some 300 feet under the earth’s surface. Traveling in a vacuum colder than deep space (minus 456 degrees Fahrenheit), the beams will approach the speed of light, making 11,245 circuits a second. Their acceleration will require roughly the same energy input that it takes to power Geneva. Then the particles in the beams will collide, and all of Atlas’ state-of-the-art machinery will strain to detect the fallout. Each collision will cause an explosion similar to the Big Bang, and turn the particle accelerator into a sort of time machine, creating conditions almost identical to those experienced less than a second after the universe came fizzing and broiling into being.
Among the many things scientists are hoping to find, the prize discovery will be the Higgs Boson, named after the University of Edinburgh physicist Peter Higgs, an elusive particle that scientists believe gives everything in the universe its mass, and hence its weight.Its confirmation will not be easy. The Higgs, like most particles worth searching for, will remain undetectable. All that will be visible to even the massive Atlas will be the stream of decay it leaves in its wake. There will be ghosts in this giant machine, and should scientists catch them, the weight on Atlas’ shoulders will be explained, and one of the fundamental mysteries of the universe will be shrugged off. hhhhAt CERN, The sense of excitement is palpable. Soon, physicists from universities across 37 countries will gather behind a concrete wall or in front of computers across the world, and watch as some of the universe’s mysteries explode and scatter in front of them. The vast majority of particles in the accelerator’s two beams are so small they will miss each other and simply continue around the track. But an estimated 20 of every 200 billion will crash head-on. Debris will scatter in all directions, shooting into hypersensitive detectors. Scientists will then scan through the detritus. They will be looking for many things, but none more important than the Higgs.To our current understanding of the universe, there is nothing more crucial – and more mysterious – than the Higgs Boson particle. A collection of these particles makes up the Higgs field, a pervasive field that gives everything in the universe its mass. As other particles move through the field – as they do constantly, since the field is everywhere – they pick up mass; it’s like pulling a weightless pearl necklace through a jar of honey. Without the Higgs Boson, everything in the universe would be insubstantial and ethereal. The Higgs, or God Particle, makes things tangible.But there’s a problem. Since the 1960s, when Professor Higgs theorized the particle while on a walk through Scotland’s mountainous Cairngorms, all efforts to detect it have failed. Indeed, the reason for this massive machine is that, in many areas of particle physics and at least for the moment, scientists have reached the limitation of the human brain. Theories have run their course; scientists now need evidence. There are many extraordinary theories like the Higgs field that explain away certain gaps in our current understanding of the universe – String Theory is another of the most ambitious and well-known – but none of them can be proved by the evidence from telescopes and the dozens of other, smaller particle accelerators currently operating around the world. To break the impasse, scientists need a flash of inspiration. This will either come by a particle streaking across one of the LHC detectors, or in the brain of a once-in-a-generation genius; no one thought Newton could be revised until Einstein started daydreaming at a patent office in Bern.
“Theorists have come to the point where we need something, even the smallest hint, to point us in the right direction,” said Chris Parkes, a physicist from the University of Glasgow working on one of the LHC’s four detectors. “Even if we don’t find anything – and that’s very unlikely – that will tell us a lot in itself. A lot of theorists are waiting for guidance from the LHC. Everyone is holding their breath.”****If the universe does decide to reveal some of its secrets, CERN would be an appropriate setting. The accelerator is nestled in a grand geological amphitheater – surrounded by the snow-capped Jure and the Alps – and the sky at night is usually clear. The streets are named after great scientists – Feynman Street, Oppenheimer Street, etc. – as particle physicists (mostly young men, mostly white) stroll in the paths of giants. The center has a dated feel, redolent of archive footage from Los Alamos and early weapons programs. Many of the hangars constructed when the center was built in the 1950s remain, and defunct rotary emergency phones hang on the walls.So close to deadline, there is no time for physicists’ well-known egos to interrupt the work. Scientists who might have once considered themselves rivals work in frenzied collaboration. At one of the accelerator’s four scanners recently, David Websdale of Imperial College London, a leader in his field, lay on his side helping to install a component on one of LHC’s four sensors. A few yards from him, Jacque Le Francois, a European medal-winner, spoke animatedly with an engineer installing piping.Get these physicists talking about their work, and they will tell you there are two types of theories: elegant and messy. Almost all believe the universe conforms to the former. God does not play dice with the universe, Einstein insisted. Every major breakthrough in physics so far has shown the universe to be ordered, sensical and elegant; the more we get to know her, the more the universe seems to always choose a garment from the rack that is a perfect fit.(Charmingly, scientists are unembarrassed about describing their poetical admiration for the workings of the cosmos; they have named two of the quarks the LHC will be studying “Truth” and “Beauty,” in the Keatsean sense that the two are interchangeable.)The problem is that the Standard Model, which incorporates all that is known about the interaction of subatomic particles and is the closest physicists currently have to a theory of everything, is becoming increasingly awkward and messy.It has holes in it. Some of these gaps can be plugged elegantly. By explaining how particles get their mass, the Higgs Boson does just that. But there are other problems to which there are no easy solutions.
For one, the universe is expanding and despite all the gravitational forces that should be reining it in and slowing it down, it is expanding faster and faster. No one knows why. What’s more, spiral galaxies like our own Milky Way are spinning so fast they should spin out of control and scatter their contents across the cosmos. But something seems to be cocooning the galaxies, keeping them intact. No one knows what.For the moment, scientists have called these unknowns “dark energy” and “dark matter,” respectively. The sinister names are misleading. Physicists view ignorance as the enemy, so anything unknown is “dark.” In reality, dark matter and dark energy are vital to the survival and function of the cosmos; in fact, they are more important than matter; dark matter and dark energy make up 94 percent of the universe.(This, of course, puts man’s importance into humbling and terrifying relief. “We’re just a bit of pollution,” American physicist Lawrence Krause said recently. “If you got rid of us, and all the stars and all the galaxies and all the planets and all the aliens and everybody, then the universe would be largely the same. We’re completely irrelevant.”)**** When it starts up, CERN will explore these inconceivably vast mysteries at an inconceivably tiny level. It’s like diagnosing a patient by studying her blood work. The corpuscular sheds light on the mammoth whole. At CERN, physicists are a hair’s breadth away from unlocking some of the innumerable mysteries that continue to confound us.What strikes a person walking through CERN’s massive interior, however, is not how much we don’t know but how much we do. In the beginning there was an explosion. The explosion was so powerful it sent the universe shooting out into nothingness at a rate that is still accelerating. Against all the odds and many years later, the dense, inorganic debris from this massive explosion met, snaked around each other like lovers, and burst into life. DNA was, in every sense that matters, a virgin birth.Now, nearly 14 billion years after it all started, and 4 billion years after their ancestors first floated to the top of the primordial soup, a team of men and women are building a machine to probe the vast and unknowable universe, and man’s tiny and inconsequential place in it. As he fiddles with a component of the Atlas sensor, one of the physicists takes a break to stretch his back. He wanders outside. The sun is passing overhead. In its early spring warmth, he smiles.
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