There are four collaborations, dubbed BRAHMS, PHENIX, PHOBOS and STAR, working at Brookhaven's Relativistic Heavy Ion Collider (RHIC). All of them study what happens when two interacting beams of gold ions smash into one another at great velocities, resulting in thousands of subatomic collisions every second. When the researchers analyzed the patterns of the atoms' trajectories after these collisions, they found that the particles produced in the collisions tended to move collectively, much like a school of fish does. Brookhaven's associate laboratory director for high energy and nuclear physics, Sam Aronson, remarks that "the degree of collective interaction, rapid thermalization and extremely low viscosity of the matter being formed at RHIC make this the most nearly perfect liquid ever observed."
Some observations of the characteristics of this super liquid match those predicted for a type of matter called a quark-gluon plasma (QGP), which is theorized to have existed just microseconds after the big bang. One large discrepancy, however, is that QGP was predicted to behave like a gas. "The current findings don't rule out the possibility that this new state of matter is in fact a form of the quark-gluon plasma," Aronson says, "[it is] just different from what had been theorized." Measurements collected over the coming years of planned experiments at RHIC should help the physicists to resolve the discrepancy. The teams' results will be published in the journal Nuclear Physics A.