The two men developed their ideas independently of each other in the 1960s and they seemed to underpin the whole Standard Model of physics, which offered a framework for how the universe works. Yet their theory was only confirmed last year when researchers at the CERN laboratory in Geneva discovered the so-called Higgs boson, or particle, in a major breakthrough.
To track down the elusive subatomic unit -- sometimes referred to by laymen as the "God particle" -- thousands of scientists at CERN, the European Organization for Nuclear Research, had to build the world's biggest atom smasher. The $10 billion Large Hadron Collider operates in a 17-mile (27-kilometer) tunnel beneath the Swiss-French border.
"I am overwhelmed to receive this award and thank the Royal Swedish Academy," the 84-year-old Higgs said in a statement released by the University of Edinburgh, where he is a professor emeritus. "I hope this recognition of fundamental science will help raise awareness of the value of blue-sky research."
Englert, 80, thanked all those who helped him in his research and said he could not have imagined getting a Nobel Prize when he started the work 50 years ago.
"You don't work thinking to get the Nobel Prize. That's not how you work," said Englert, a professor emeritus at the Universite Libre de Bruxelles in Belgium. "(Still) we had the impression that we were doing something that was important, that would later on be used by other researchers."
For once, the Nobel physics judges picked a prize that had been widely anticipated; their choices are normally hard to predict. However, the announcement was delayed by an hour, which is highly unusual.
The academy said on Twitter it was "still in session" when it was supposed to make its announcement, but didn't explain the reason for the delay. It could be a while before the world finds out why, because the academy's deliberations are kept secret for 50 years.
Permanent Secretary Staffan Normark said the academy couldn't reach Higgs by phone on Tuesday, but wouldn't say whether that's what caused the delay.
By awarding only the men behind the theory, the prize committee avoided the tricky issue of picking someone at CERN to share the award. Nobels can be shared by no more than three people.
Academy member Ulf Danielsson noted that the prize citation also honored the work done at CERN, even though it didn't single out any of its scientists.
"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.
"I'm thrilled that this year's Nobel Prize has gone to particle physics," said CERN Director General Rolf Heuer. He added that the discovery of the particle at CERN "marks the culmination of decades of intellectual effort by many people around the world."
In the CERN cafeteria, applause broke out and champagne bottles popped. Heuer told everyone to applaud themselves for their work.
Englert and Higgs were trying to provide an answer to a riddle: why do certain fundamental particles have mass. They proposed the existence of an invisible field that sprawls through space like a net. The building blocks of matter, they suggested, acquired mass shortly after the Big Bang, when they were trapped by this field. Much later, as the universe cooled, they formed atoms. 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 at CERN were able to confirm the particle's existence in July 2012.
Only about one collision per trillion will produce one of the Higgs bosons in the giant atom collider, and it took CERN some time after the discovery of a new "Higgs-like" boson to decide that the particle was, in fact, very much like the Higgs boson expected in the original formulation.
The phrase "God particle" was coined by Nobel Prize-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 as an easier way of explaining the theory -- was really meant to convey that he felt it was the "goddamn particle," because it proved so hard to prove.
Michael Turner, president of the American Physical Society, an organization of physicists, said the Higgs particle captured the imagination of the public.
"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 like the nature of so-called dark energy and dark matter, he said.
The physics prize was the second of this year's Nobel awards to be announced. On Monday, the Nobel Prize in medicine was given to American scientists James Rothman, Randy Schekman and Thomas Sudhof for discoveries about how key substances are moved around within cells.
The prizes, established by Swedish industrialist and Alfred Nobel, will be handed out on Dec. 10 -- the anniversary of his death in 1896. Each prize is worth 8 million Swedish kronor ($1.2 million).
Jordans reported from Berlin. Associated Press John Heilprin in Geneva and Malcolm Ritter in New York contributed to this report.
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