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UPTON, N.Y. (AP) -- Physicists said Wednesday they had created a new form of matter strongly resembling the stuff of the universe one-thousandth of a second after its birth.
This matter is called quark-gluon plasma and physicists believe it is key in understanding both the dawn of the universe and the interior of atomic nuclei.
"The matter we have created has properties that have never before been observed,'' said William Zajc of Columbia University, one of hundreds of researchers working on the project at Brookhaven National Laboratory.
Whether this new matter actually qualifies as the long-sought quark-gluon plasma is an issue for debate, but all of the scientists who heard the evidence agreed that what they've seen so far looks good.
"There is still work to do,'' said Peter Jacobs of Lawrence Berkeley National Laboratory, who expressed hesitation about the findings.
He and his colleagues have submitted three papers describing their results to the journal Physical Review Letters.
Quark-gluon plasma offers a glimpse at both the birth of the universe 13 billion years ago and the incredibly tiny realm inside atomic nuclei today.
Since its birth, the universe has gradually cooled from more than 100 trillion degrees to today's relatively frigid conditions. As temperatures fell below about a trillion degrees, quarks and gluons went from a free state into the confines of protons and neutrons. By reversing that process, even for only an instant, physicists hope to learn how it occurred.
Similarly, smashing apart gold atoms could shed light on how quarks and gluons arrange themselves inside protons and neutrons, and how those bigger particles in turn form nuclei.
At Wednesday's presentation, the researchers described experiments in which gold atoms were accelerated nearly to the speed of light and then smashed together. These collisions were so violent that the debris they produced briefly reached temperatures of one trillion degrees centigrade, the hottest and densest conditions ever created in a laboratory.
Brookhaven's Relativistic Heavy Ion Collider, or RHIC, was built to smash atomic nuclei so violently that their most fundamental components _ quarks and gluons _ are liberated from their normal tight confinement and momentarily released into a seething hot soup. The amount of energy required to produce that transformation is so high that it has almost certainly not existed in nature since the dawn of the universe.
Three years ago, physicists at Europe's CERN physics laboratory announced that they had seen fleeting signs of quark-gluon plasma in the aftermath of collisions between lead nuclei. But many physicists dismissed the claim as unconvincing and a full scientific paper was never published.
At 10 times the energy of the CERN lead collisions, RHIC's gold experiments offer a much better opportunity to produce and study the new realm, said John Harris, a theoretical physicist at Yale University.
"At this highest energy we're seeing characteristics that are much like what we expected,'' Harris said.
Other physicists cautioned that the Brookhaven experiments have not yet shown that the new matter has all the characteristics of a quark-gluon plasma. It clearly has sufficient density, Jacobs said. But so far the experiments have not shown that individual quarks and gluons are floating around in it completely free of their nuclear constraints.
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