RECORD IS BROKE

To get a grasp on what holds these visible forms of matter together—everything from stars to planets to people—you have to understand how quarks and

gluons interact. That's the essence of quark matter physics—and the Quark Matter 2012 international conference, taking place in Washington, D.C., August 12-18. "We're studying the 99 percent of the mass of the visible universe that isn't explained by the Higgs," says Peter Steinberg, a physicist at the U.S. Department of Energy's Brookhaven National Laboratory and a participant in the Quark Matter conference.

Visible matter, he explains, is everything made of atoms, which get their mass mainly from the protons and neutrons that make up atomic nuclei. The electrons orbiting around the nucleus contribute practically nothing. But the protons and neutrons, each made of three quarks, are much more massive than the sum of their constituent particles. Where does all the "extra" mass come from?

The answer, physicists believe, lies in how the quarks interact via the exchange of gluons, massless particles that hold the quarks together via nature's strongest force, and interactions among the gluons themselves. To tease apart the features of this force, which gets stronger and stronger if you try to pull the subatomic quarks apart, physicists accelerate atomic nuclei (a.k.a. heavy ions) to near light speed, where the gluons become dominant, and then steer them into head-on collisions at particle accelerators like the Relativistic Heavy Ion Collider (RHIC) at Brookhaven and the Large Hadron Collider in Europe.