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A half-century scientific quest culminated early Wednesday as physicists announced the discovery of a new subatomic particle - one theorized to be so fundamental that without it, nothing could exist.
Dubbed the Higgs boson - or the "God particle," to the chagrin of scientists - the particle is thought to create a sort of force field that permeates the universe, imbuing everything that we can see and touch with the fundamental property known as mass.
"As a layman, I now say, I think we have it," said Rolf-Dieter Heuer, director general of CERN, the European Organization for Nuclear Research, immediately after physicists presented compelling evidence for the new particle at a seminar in Geneva.
"Do you agree?" he asked the several hundred scientists packing CERN's main auditorium.
Applause broke out. The video feed from CERN showed Peter Higgs, the University of Edinburgh physicist who theorized the existence of this exotic particle in 1964, tearing up.
"We have a discovery," Heuer said. "We have discovered a new particle consistent with the Higgs boson. It's a historic milestone today."
The scientists at CERN then stood, applauded and cheered for a full minute.
"I have the impression you are all happy," Heuer said.
Moments later, Higgs stood and said, "For me, it's really an incredible thing that happened in my lifetime."
While there were typical scientist-esque notes of caution - a CERN statement called the discovery "preliminary" - scientists around the world celebrated the moment.
A video feed from Melbourne, Australia, where an international physics conference is set to begin, showed an auditorium packed with cheering scientists.
"One of the most exciting weeks of my life," said Joe Lykken, a theoretical physicist who worked on one of the two CERN experiments that found evidence of the new particle.
At Fermilab, long-time home of the U.S. high-energy physics community, some 300 people stuffed into two rooms to watch a video feed from Geneva, said Don Lincoln, a Fermilab physicist who contributed to the CERN experiments.
"It's incredible," Lincoln said. "People were riveted. Discovery is what scientists live for."
At Columbia University in New York, 75 people shared a bottle of champagne brought by experimental physicist Michael Tuts, one of the more than 6,000 scientists who contributed to the discovery.
"I'm still astonished that at 3 a.m. on the Fourth of July you can gather" so many people excited about the arcane field of subatomic physics, Tuts said. High school students, undergraduates, graduate students and professors all shared the bubbly after the discovery became clear.
"We toasted this," Tuts said. "It was great fun to see the culmination of years and years of work."
With a self-imposed deadline of July 4 - set two years ago to line up with the conference in Melbourne - CERN physicists raced in recent days to collect and analyze enough data to say they had, indeed, found a new particle that looked like the long-sought Higgs.
As late as Tuesday, two teams pored over results from the last run of high-energy subatomic collisions at the huge Large Hadron Collider straddling the French-Swiss border.
"It's the last month of running that did it," said Joe Incandela, spokesman for one of the two experiments at CERN that found evidence of the Higgs, during his presentation Wednesday morning.
The discovery of the new particle completes what's known as the Standard Model of particle physics, the equivalent of chemistry's Periodic Table. The Standard Model lists and arranges the particles and forces of nature. Many of the particles were predicted long before they were found - and the Higgs was the last holdout, and the most important.
That's because it is thought to give rise to the "Higgs field," a sort of force field the permeates everything.
"We know the Higgs is at the center of everything," Lykken said. "This is why (Nobel Prize-winning physicist) Leon Lederman called it the God particle. It talks to all the other particles in some fundamental way."
When the other particles that make up the stuff of the universe - protons, neutrons, electrons and so on - interact with the Higgs field, they acquire the trait known as mass. More massive objects get tangled up in the field - and hence, slowed down as they move - more than less massive objects.
One way to think of the Higgs field: It's the water the entire universe swims in.
The CERN physicists did not see this new particle directly, because it disintegrates too quickly. Rather, they divined its existence from sifting through the debris of millions of high-energy subatomic collisions and then searching for clues that the Higgs had been there. It's like divining the presence of an elusive snow leopard by studying thousands of criss-crossed paw prints.
But by studying these traces, the CERN physicists saw a "bump" in their data consistent with a Higgs boson.
Two independent teams, working on two separate particle detectors, arrived at similar results - a kind of cross-check. The two teams, each with more than 3,000 scientists, were not to share their results with each other before the seminar at CERN Wednesday.
To find this tiny particle, scientists built the biggest of machines - a 17-mile ring under the French-Swiss border called the Large Hadron Collider. At two points along the ring, they installed cathedral-sized detectors that capture traces of high-energy collisions of protons. Inside this subatomic wreckage, both detectors saw evidence for a subatomic particle with a mass of around 125 giga-electron volts - or about 125 times the mass of a proton.
CERN announced last December that it was homing in on the Higgs, but cautioned that it needed a new batch of high-energy collisions to gain confidence that scientists were seeing something real and not a random bump in the data.
The hunt for the Higgs represented a test for theorists and, at a more nuts-and-bolts level, for the public officials who decided to green-light the extraordinarily elaborate and tricky endeavor to find a hypothetical particle.
An explosion in one of the LHC's sensitive superconducting magnets in September 2008 delayed operations for more than year. But this biggest of big science experiments now appears to have paid off.
Mass, not weight
The idea of the Higgs, or something like it, has been around since 1964, when it was first hypothesized by Peter Higgs. The Standard Model of physics had a hole in it - one that needed to be filled by a particle that imbues everything with mass. It became known as the Higgs boson - and its discovery, many scientists say, will now surely garner a Nobel Prize.
Mass is not the same thing as weight, although the two concepts are easily confused. An object has mass even in outer space. Mass is an object's resistance to being shoved around - its inertia.
A photon, which is a light particle, has no mass because it zips through the Higgs ocean without interacting with it. Light speed is the cosmic speed limit for this reason - because nothing can have less-than-zero interaction with the Higgs field. (Mass can then be described as the quality that keeps everything from moving at the speed of light.)
A neutrino has an extremely small mass - it moves at nearly the speed of light (and not faster, as some European scientists suggested last year erroneously before finding a loose cable was the culprit for their weird results).
Ordinary matter that comprises the bulk of stars, planets and human beings is relatively massive. The most massive particles move like someone trying to walk through neck-high water.
This notion of a field that gives particles mass has been essential to understanding the way the universe is put together. Columbia University physicist Brian Greene, speaking prior to the announcement, said, "Everything I've ever done, directly or indirectly, has something to do with a Higgs-like field."
The discovery of the Higgs is the latest reminder that the universe can be understood through mathematics.
"It makes you feel good as a theorist," Greene said. "Math really does provide a window on reality!"