ASPEN, Colo. — Physicists said Wednesday they had discovered a subatomic particle that looks like the Higgs boson, a potential key to understanding why elementary particles have mass and indeed to the existence of diversity and life in the universe.
‘‘I think we have it,’’ Rolf-Dieter Heuer, the director general of CERN, said in an interview from his office outside Geneva, calling the discovery ‘‘a historic milestone.’’
His words signaled what is probably the beginning of the end for one of the longest, most expensive searches in the history of science. If scientists are lucky, the discovery could lead to a new understanding of how the universe began.
The discovery was announced at the Large Hadron Collider in Switzerland. Heuer and others said it was too soon to know for sure whether the new particle, which weighs in at 125 billion electron volts, one of the heaviest subatomic particles yet, fits the simplest description given by the Standard Model, the theory that has ruled physics for the last half-century, or whether it is an impostor, a single particle, or even the first of many particles yet to be discovered.
The latter possibilities are particularly exciting to physicists because they could point the way to new deeper ideas, beyond the Standard Model, about the nature of reality. For now, some physicists are calling it a ‘‘Higgslike’’ particle.
‘’It’s great to discover a new particle, but you have find out what its properties are,’’ said John Ellis, a theorist at CERN, the European Organization for Nuclear Research.
Joe Incandela, of the University of California, Santa Barbara, a spokesman for one of two groups reporting data Wednesday, called the discovery ‘‘very, very significant.’’
‘’It’s something that may, in the end, be one of the biggest observations of any new phenomena in our field in the last 30 or 40 years, going way back to the discovery of quarks, for example,’’ he said.
Here at the Aspen Center for Physics, a retreat for scientists that will celebrate its 50th birthday Saturday, the sounds of cheers and popping corks reverberated early Wednesday against the Sawatch Range through the Roaring Fork Valley of the Rockies, as bleary-eyed physicists watched their colleagues read off the results in a webcast from CERN. It was a scene duplicated in Melbourne, Australia, where physicists had gathered for a major conference, as well as in Los Angeles, Chicago, Princeton, N.J., New York, London, Boston, and beyond — everywhere that members of a curious species have dedicated their lives and fortunes to the search for their origins in a dark universe.
“The obsession of all physicists for the last 30 years has been what gives particles mass — what makes some things go fast and some things go slowly when you push them along,” said Larry Sulak, a professor at Boston University who has been investigating that question for decades. “This was the most important particle in the most early times of the creation of the universe. It gives us a direct picture back to the first nanosecond of the universe.”
At CERN, 1,000 people stood in line all night to get into the auditorium, according to Guido Tonelli, a CERN physicist who said the atmosphere was like a rock concert. Peter Higgs, the University of Edinburgh theorist for whom the boson is named, entered the meeting to a standing ovation.
Confirmation of the Higgs boson or something very much like it would constitute a rendezvous with destiny for a generation of physicists who have believed in the boson for half a century without ever seeing it. And it affirms a grand view of a universe ruled by simple and elegant and symmetrical laws, but in which everything interesting in it, like ourselves, is a result of flaws or breaks in that symmetry.
According to the Standard Model, the Higgs boson is the only visible and particular manifestation of an invisible force field, a cosmic molasses that permeates space and imbues elementary particles that would otherwise be massless with mass. Particles wading through it would gain heft.
Without this Higgs field, as it is known, or something like it, physicists say all the elementary forms of matter would zoom around at the speed of light, flowing through our hands like moonlight. There would be neither atoms nor life.
Physicists said they would probably be studying the new Higgs particle for years. Any deviations from the simplest version of the boson — and there are hints of some already — could open a gateway to new phenomena and deeper theories that answer questions left hanging by the Standard Model.
‘‘If the boson really is not acting standard, then that will imply that there is more to the story — more particles, maybe more forces around the corner,’’ Neal Weiner, a theorist at New York University, wrote in an e-mail. ‘‘What that would be is anyone’s guess at the moment.’’
Globe correspondent Colin Young contributed to this report.