Physicists Closing in on Understanding the Primordial Universe

Photo of the ALICE detector at CERN. Photo courtesy of CERN.

Slamming barely nothing together is bringing scientists ever-closer to understanding the weird states of matter present just milliseconds after the creation of the Universe in the Big Bang. This is according to physicists from CERN and Brookhaven National Laboratory, presenting their latest findings at the Quark Matter 2012 conference in Washington, DC.

By smashing ions of lead together within CERN’s lesser-known ALICE heavy-ion experiment, physicists said Monday that they created the hottest man-made temperatures ever. In an instant, CERN scientists recreated a quark-gluon plasma — at temperatures 38 percent hotter than a previous record 4-trillion degree plasma. This plasma is a subatomic soup and the very unique state of matter thought to have existed in the earliest moments after the Big Bang. Earlier experiments have shown these particular varieties of plasmas behave like perfect, frictionless liquids. This finding means that physicists are studying the densest and hottest matter ever created in a laboratory; 100,000 times hotter than the interior of our Sun and denser than a neutron star.

CERN’s scientists are just coming off of their July announcement of the discovery of the elusive Higgs boson.

“The field of heavy-ion physics is crucial for probing the properties of matter in the primordial universe, one of the key questions of fundamental physics that the LHC and its experiments are designed to address. It illustrates how in addition to the investigation of the recently discovered Higgs-like boson, physicists at the LHC are studying many other important phenomena in both proton–proton and lead–lead collisions,” said CERN Director-General Rolf Heuer.

According to a press release, the findings help scientists understand the “evolution of high-density, strongly interacting matter in both space and time.”

Meanwhile, scientists at Brookhaven’s Relativistic Heavy Ion Collider (RHIC), say they have observed the first glimpse of a possible boundary separating ordinary matter, composed of protons and neutrons, from the hot primordial plasma of quarks and gluons in the early Universe. Just as water exists in different phases, solid, liquid or vapor, depending on temperature and pressure, RHIC physicists are unraveling the boundary where ordinary matter starts to form from the quark gluon plasma by smashing gold ions together. Scientists are still not sure where to draw the boundary lines, but RHIC is providing the first clues.

The nuclei of today’s ordinary atoms and the primordial quark-gluon plasma, or QGP, represent two different phases of matter and interact at the most basic of Nature’s forces. These interactions are described in a theory known as quantum chromodynamics, or QCD. Findings from RHIC’s STAR and PHENIX show that the perfect liquid properties of the quark gluon plasma dominate at energies above 39 billion electron volts (GeV). As the energy dissipates, interactions between quarks and the protons and neutrons of ordinary matter begin to appear. Measuring these energies give scientists signposts pointing to the approach of a boundary between ordinary matter and the QGP.

“The critical endpoint, if it exists, occurs at a unique value of temperature and density beyond which QGP and ordinary matter can co-exist,” said Steven Vigdor, Brookhaven’s Associate Laboratory Director for Nuclear and Particle Physics, who leads the RHIC research program. “It is analogous to a critical point beyond which liquid water and water vapor can co-exist in thermal equilibrium, he said.

While Brookhaven’s particle accelerator cannot match CERN’s record-setting temperature conditions, scientists at the U.S Energy Department lab say the machine maps the “sweet spot” in this phase transition.

Image caption: The nuclear phase diagram: RHIC sits in the energy “sweet spot” for exploring the transition between ordinary matter made of hadrons and the early universe matter known as quark-gluon plasma. Courtesy of the U.S. Department of Energy’s Brookhaven National Laboratory.

John Williams is a science writer and owner of TerraZoom, a Colorado-based web development shop specializing in web mapping and online image zooms. He also writes the award-winning blog, StarryCritters, an interactive site devoted to looking at images from NASA’s Great Observatories and other sources in a different way. A former contributing editor for Final Frontier, his work has appeared in the Planetary Society Blog, Air & Space Smithsonian, Astronomy, Earth, MX Developer’s Journal, The Kansas City Star and many other newspapers and magazines.