"You don't work thinking to get the Nobel Prize," said Englert, a retired professor at the Free University of Brussels. Still, "we had the impression that we were doing something that was important, that would later on be used by other researchers."
The Nobel selection committees are notoriously cautious, often allowing decades to elapse before honoring a scientific breakthrough, and their choices are hard to predict. But this time, the prize went to people who were widely expected to get it.
"In CERN here, most all of the physicists I know, about 95 percent, expected those two would win it. The question was if there would be a third and who it would be," said Joe Incandela, a professor of physics at the University of California at Santa Barbara and leader of the CMS experiment, one of the two groups that discovered the Higgs particle.
Before the announcement, there had been questions over whether a group of American scientists who published a paper shortly after Higgs would also be honored, or whether any of the thousands of scientists at CERN would share in the prize, too.
But that would have been a tricky decision for the judges, since each Nobel Prize can go to only three winners.
Ulf Danielsson, a member of the Royal Swedish Academy of Sciences, which awards the physics prize, noted that the prize citation also honored the work done at CERN.
"This is a giant discovery. It means the final building block in the so-called Standard Model for particle physics has been put in place, so it marks a milestone in the history of physics," Danielsson said.
The two winners will share a prize worth 8 million Swedish kronor ($1.2 million). The Nobel Prizes, established by Swedish industrialist Alfred Nobel, have been given out since 1901.
CERN Director General Rolf Heuer said he was thrilled for Higgs and Englert, while many of the thousands of scientists who worked there broke into applause when the announcement was made after an unusual and unexplained one-hour delay. (It could be a while before the world finds out the reason for the delay, because the academy's deliberations are kept secret for 50 years.)
Englert and Higgs were trying to provide an answer to a riddle: How did matter form soon after the Big Bang?
They proposed the existence of an invisible field that sprawls through space like a net. The building blocks of matter, they suggested, acquired mass when this field trapped them. Much later, as the universe cooled, they formed atoms that eventually became stars and planets.
To detect the field, the scientists suggested looking for the Higgs boson, because all fields are associated with a particle. Decades would pass before scientists were able to confirm the existence of this particle.
Only about one collision per trillion will produce a Higgs boson in the giant atom collider, and it took CERN several months after the discovery of a new "Higgs-like" boson to conclude that the particle was, in fact, very much like the one expected in the original formulation.
The phrase "God particle" was coined by Nobel-winning physicist Leon Lederman, but it's disliked by most physicists because it connotes the supernatural. Lederman said later that the phrase mostly used by laymen was really meant to convey that he felt it was the "goddamn particle," because it proved so hard to find.
Michael Turner, president of the American Physical Society, an organization of physicists, said the Higgs particle captured the public's imagination.
"If you're a physicist, you can't get in a taxi anywhere in the world without having the driver ask you about the Higgs particle," said Turner, a cosmologist at the University of Chicago.
Turner said the Higgs is the first in a class of particles that scientists think played a role in shaping the universe. That means it points the way to tackling mysteries such as the nature of dark energy and dark matter, he said.
The physics prize was the second of this year's Nobels to be announced. On Monday, the Nobel in medicine was given to U.S. scientists James Rothman, Randy Schekman and Thomas Sudhof for discoveries about how key substances are moved around within cells.
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Jordans reported from Berlin. Associated Press writers John Heilprin in Geneva and Malcolm Ritter in New York contributed to this report.
