It was a big day for a very small particle that, when all was said and done, remained invisible, indeed still theoretical.
But even if scientists couldn't claim Tuesday that they had "discovered" the fabled Higgs boson, they were exultant, convinced that their experiments at the Large Hadron Collider near Geneva are zeroing in on a particle believed to be essential to the fabric of the universe.
"We know the goal is close," said Fabiola Gianotti, a physicist representing one of two competing teams searching for the elusive particle. "This is the nicest feeling."
Rolf-Dieter Heuer, director-general of the European Organization for Nuclear Research, or CERN, home of the Large Hadron Collider, said that another year of data need to be compiled before anyone can reach "a definitive answer on the Shakespearean question on the Higgs: To be or not to be?"
But the scientists in Geneva were leaning in one direction Tuesday: It will eventually be. The new results suggest that something roughly 125 times the mass of a proton is being created by collisions at the Large Hadron Collider. That finding could prove to be a statistical fluke; hence the cautious words by the top scientists.
The Higgs is the most sought-after particle in physics, but no one has ever seen one, even indirectly. Elaborate theories, the orthodoxies of modern particle physics, hang in the balance.
Because it has such cosmic significance, the Higgs is often referred to in the media as "the God particle," the title of a book by physicist Leon Lederman. Legend has it that a frustrated Lederman originally called it the "G--d—-n particle." The particle's more orthodox name is in honor of theorist Peter Higgs, who predicted its existence in 1964.
He said the particle creates a force field that scientists believe permeates the universe and gives particles their mass, their resistance to being shoved around. Don Lincoln, a physicist at the Energy Department's Fermilab in Illinois and a member of one of the two CERN teams, likened this force field to a pool of water. Just as a barracuda can knife swiftly through water, some subatomic particles such as electrons speed through the Higgs field, giving them very little mass. Other particles, akin to blubbery whales, create more drag, making them more massive.
The orthodox theory of particle physics, called the Standard Model, has been exceedingly successful to date. Many particles predicted by the Standard Model have subsequently been discovered in experiments.
After the Higgs announcement, physicists immediately did what physicists do: They argued about the data.
Matt Strassler, a theoretical physicist at Rutgers University, informally polled attendees at CERN: Are you convinced the Higgs has been found? Fifteen said no, one said maybe, and one brave soul said yes.
The yes came from a member of one of two CERN teams competing to find the Higgs, Tommaso Dorigo. On his blog, Dorigo titled a post "Firm Evidence of a Higgs Boson at Last!"
To that, Strassler said, "He's out on a limb."
The quarrel speaks to the nature of high-energy physics: It's all about statistics. What sounds like certainty to just about everyone is anything but to a physicist. To claim a formal discovery, physicists want to see uncertainty squashed down to less than a 1-in-a-million prospect.
At the end of a news conference Tuesday, Heuer predicted the hunt will end soon after the Large Hadron Collider, now fallow for winter, restarts in March. "See you next year with a discovery."