For physicists, it was a moment like landing on the moon or the discovery of DNA.
The focus was the Higgs boson, a subatomic particle that exists for a mere fraction of a second. Long theorized but never glimpsed, the so-called God particle is thought to be key to understanding the existence of all mass in the universe. The revelation Wednesday that it â€" or some version of it â€" had almost certainly been detected amid more than hundreds of trillions of high-speed collisions in a 17-mile track near Geneva prompted a group of normally reserved scientists to erupt with joy.
Peter Higgs, one of the scientists who first hypothesized the existence of the particle, reportedly shed tears as the data were presented in a jampacked and applause-heavy seminar at CERN, the European Organization for Nuclear Research.
"It's a gigantic triumph for physics," said Frank Wilczek, an MIT physicist and Nobel laureate. "It's a tremendous demonstration of a community dedicated to understanding nature."
The achievement, nearly 50 years in the making, confirms physicists' understanding of how mass â€" the stuff that makes stars, planets and even people â€" arose in the universe, they said.
It also points the way toward a new path of scientific inquiry into the mass-generating mechanism that was never before possible, said UCLA physicist Robert Cousins, a member of one of the two research teams that have been chasing the Higgs boson at CERN.
"I compare it to turning the corner and walking around a building â€" there's a whole new set of things you can look at," he said. "It is a beginning, not an end."
Leaders of the two teams reported independent results that suggested the existence of a previously unseen subatomic particle with a ma ss of about 125 billion to 126 billion electron volts. Both groups got results at a "five sigma" level of confidence â€" the statistical requirement for declaring a scientific "discovery."
"The chance that either of the two experiments had seen a fluke is less than three parts in 10 million," said UC San Diego physicist Vivek Sharma, a former leader of one of the Higgs research groups. "There is no doubt that we have found something."
But he and others stopped just shy of saying that this new particle was indeed the long-sought Higgs boson. "All we can tell right now is that it quacks like a duck and it walks like a duck," Sharma said.
In this case, quacking was enough for most.
"If it looks like a duck and quacks like a duck, it's probably at least a bird," said Wilczek, who stayed up past 3 a.m. to watch the seminar live over the Web while vacationing in New Hampshire.
Certainly CERN leaders in Geneva, even as they referred to their discovery simply as "a new particle," didn't bother hiding their excitement.
The original plan had been to present the latest results on the Higgs search at the International Conference on High Energy Physics, a big scientific meeting that began Wednesday in Melbourne.
But as it dawned on CERN scientists that they were on the verge of "a big announcement," Cousins said, officials decided to honor tradition and instead present the results on CERN's turf.
The small number of scientists who theorized the existence of the Higgs boson in the 1960s â€" including Higgs of the University of Edinburgh â€" were invited to fly to Geneva.
For the non-VIP set, lines to get into the auditorium began forming late Tuesday. Many spent the night in sleeping bags.
All the hubbub was due to the fact that the discovery of the Higgs boson is the last piece of the puzzle needed to complete the so-called Standard Model of particle physics â€" the big picture that describes the s ubatomic particles that make up everything in the universe, and the forces that work between them.
Over the course of the 20th century, as physicists learned more about the Standard Model, they struggled to answer one very basic question: Why does matter exist?
Higgs and others came up with a possible explanation: that particles gain mass by traveling through an energy field. One way to think about it is that the field sticks to the particles, slowing them down and imparting mass.
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