Install

Get the latest updates as we post them — right on your browser

. Last Updated: 07/27/2016

Big Bang Matter Created in Swiss Lab




Scientists at Europe's premier high-energy physics facility announced Thursday that they have created a "new state of matter" that has not existed since a few millionths of a second after the Big Bang that generated the cosmos.


The new state, which the scientists infer from different aspects of seven experiments over the past six years, is presumably one in which tiny sub-nuclear particles called quarks and gluons are squeezed and heated to such a stupendous extent that they can move freely.


This never happens under ordinary conditions. In all but extreme circumstances, quarks are always tightly bound into groups of three in the form of neutrons and protons, or into short-lived pairs in particles called mesons. There is no such thing as a free quark.


Although theory indicates quarks might become unbound in an ultra-high energy environment, free-moving quarks would last have been seen just after the Big Bang, before the quark-and-gluon soup cooled and congealed into protons and neutrons.


Luciano Maiani, general director of the CERN laboratory in Geneva where the new work was done, said the new finding "verifies an important prediction of the present theory of fundamental particles." It is also "an important step forward in the understanding of the early evolution of the universe."


Several experts in the United States called the claim of a "new state of matter" premature. Among other things, no one knows what a free-quark condition is supposed to look like. As one high-energy research veteran put it, "there is definitely no smoking gun" to prove the new state had been observed.


But many physicists found the CERN achievement promising for the next stage of similar research, slated to begin this summer at Brookhaven National Laboratory's new Relativistic Heavy Ion Collider on Long Island.


"Those of us working on RHIC are very encouraged by these results," BNL senior scientist Thomas Ludlam said.


CERN's "evidence is not conclusive, but it is very interesting and points in the direction of the creation" of a new state, said Robert Jaffe, director of the Center for Theoretical Physics at the Massachusetts Institute of Technology in Cambridge, Massachusetts. "It is perfectly reasonable for the CERN people to want to tie it all together," he said.


In pursuit of a new state, the CERN team smashed the nuclei of lead atoms so hard they achieved densities about 20 times greater than an ordinary atomic nucleus and temperatures more than 100,000 times as hot as the center of the sun, scientists said. Such a collision should produce so much energy that protons and neutrons would disintegrate into constituent quarks and gluons, which would be drastically compressed.


Under those circumstances, quarks and gluons are expected to behave in weird ways, thanks to a counterintuitive peculiarity of nuclear physics. The more familiar fundamental forces of nature, such as gravity or magnetism, get weaker over distance. But the so-called "strong" force that binds quarks together works in reverse: The closer the particles are, the more freely they can move about.


Theory has long predicted that if quarks and gluons could be crammed close enough and brought to high enough energies, they would create a sort of gas called a "quark-gluon plasma" in which the particles would be unconfined. It is this plasma that is thought to have filled the nascent universe microseconds after the Big Bang.


"The picture of quark-gluon plasma resembles a jigsaw puzzle, with many pieces provided by the different experiments," CERN's announcement said. "The data from any one experiment is not enough to give the full picture, but the combined results from all experiments agree and fit."


CERN officials stopped short of saying that they had achieved the quark-gluon plasma, declaring only that they had shown quark deconfinement.


"There's going to be a great deal of disagreement in the community as to whether these results are really meaningful or not," said Norman Glendenning, a scientist at Lawrence Berkeley National Laboratory.