Sunday, April 29, 2012

Brookhaven Lab's Paul Sorensen on Recreating the Early Universe at RHIC


Paul Sorensen of the Brookhaven National Laboratory's Relativistic Heavy Ion Collider (RHIC) describes the quark-gluon plasma created in the collisions of Gold nuclei accelerated to energies of up to 100 GeV at RHIC. To the surprise of the investigators at the RHIC collaborations PHENIX, BRAHMS, STAR and PHOBOS, the quark-gluon plasma behaves more like a liquid than a gas, with its constituent quarks and gluons behaving not as free particles but interacting strongly with each other and moreover, displaying very strongly correlated motion, so that the fluid has no viscosity.

The quark gluon plasma created at RHIC represents a recreation of the conditions of the early universe and results of the experiments are being analyzed for answers to questions about how the universe evolved into its present state. For example, RHIC experiments have found both parity and CP-violating events in the quark-gluon plasma, which is one channel by which the observed matter-antimatter asymmetry in the universe could have arisen. Had this asymmetry not existed, the entire universe as we know it, with the stars, galaxies and life itself would not have been possible.

But theoretical analyses also reveals dynamical analogies with the initial evolution of the universe, with the decaying inflaton field responsible for cosmological inflation having its analogy in the decaying glasma field, for example. And among other possibilities, the evolution of a non-viscous hydrodynamics from the quark-gluon plasma, it is conjectured, may include a transient Bose-Einstein condensate, a phenomenon also known in the context of inflaton dynamics.