It was also the most important, because it is thought to give rise to the “Higgs field,” a sort of force field that permeates everything.
“We know the Higgs is at the center of everything,” said Joe Lykken, a theoretical physicist who worked on one of the two CERN experiments that found evidence of the new particle. “This is why [Nobel Prize-winning physicist] Leon Lederman called it the God particle. It talks to all the other particles in some fundamental way.”
When the other particles that make up the stuff of the universe — protons, neutrons, electrons and so on — interact with the Higgs field, they acquire the trait known as mass. More-massive objects get tangled up in the field more than less-massive objects.
One way to think of the Higgs field: It’s the water the entire universe swims in.
A photon, which is a light particle, has no mass because it zips through the Higgs ocean without interacting with it. Light speed is the cosmic speed limit for this reason — because nothing can have less-than-zero interaction with the Higgs field. (Mass can then be described as the quality that keeps everything from moving at the speed of light.)
A neutrino has an extremely small mass — it moves at nearly the speed of light (and not faster, as some European scientists suggested last year erroneously before finding that a loose cable was the culprit for their weird results). Ordinary matter that makes up the bulk of stars, planets and human beings is relatively massive. The most massive particles move like someone trying to walk through neck-high water.
The CERN physicists did not see the new particle directly, because it disintegrates too quickly. Rather, they divined its existence from sifting through the debris of trillions of high-energy subatomic collisions, and then searching for clues that the Higgs had been there. It’s like divining the presence of an elusive snow leopard by studying thousands of crisscrossed paw prints.
But by studying these traces, the CERN physicists saw a “bump” in their data consistent with a Higgs boson.
The two independent teams from the ATLAS and CMS experiments served as cross-checks for each other. The teams, each with more than 3,000 scientists, were not to share their results before the seminar Wednesday at CERN.
The Large Hadron Collider creates beams of particles that move in opposite directions and then collide inside cathedral-size detectors that are parked in vast caverns along the tunnel. The detectors capture traces of the collisions. Inside this subatomic wreckage, both detectors saw evidence of a subatomic particle with a mass of about 125 giga-electron volts — or about 125 times the mass of a proton.
CERN announced in December that it was homing in on the Higgs but cautioned that it needed a new batch of high-energy collisions to gain confidence that scientists were seeing something real and not a random bump in the data.
Months of collisions pushed the data into the discovery zone.
“One of the most exciting weeks of my life,” Lykken said.
Columbia University physicist Brian Greene, speaking before the announcement, said, “Everything I’ve ever done, directly or indirectly, has something to do with a Higgs-like field.” The discovery of the Higgs is the latest reminder, he said, that the universe can be understood through mathematics.
“It makes you feel good as a theorist,” Greene said. “Math really does provide a window on reality!”
At Fermilab, longtime home of the U.S. high-energy physics community, about 300 people stuffed into two rooms to watch a video feed from Geneva, said Don Lincoln, a Fermilab physicist who contributed to the CERN experiments.
“It’s incredible,” Lincoln said. “People were riveted.”
At Columbia University in New York, 75 people shared champagne brought by experimental physicist Michael Tuts.
“It was great fun to see the culmination of years and years of work,” Tuts said.
The discovery hardly ends the quest to understand the essence of space, time, energy and matter. Among the remaining mysteries are dark matter, the unknown substance observed only through its gravitational effects, and dark energy, a cosmic force that seems to be causing the universe to expand at an accelerating rate.
Turner, the University of Chicago physicist, said after the announcement, “Okay, the particle physicists got their Number 1 wish — the Higgs. Now we cosmologists want ours — the dark-matter particle.”