Cold gas may model cosmos in lab

An exotic, ultra-cold gas named for two of the world's greatest physicists may allow scientists to recreate some of the greatest mysteries of deep space inside the comfortable confines of a laboratory.

Named for Indian physicist Satyendra Nath Bose and Albert Einstein, Bose-Einstein condensates, or BECs, are small balls of gas "whose evolution is governed by some equations that look similar to the equations that govern supernovas and neutron stars," University of Colorado physicist and Nobel laureate Eric Cornell told United Press International from Boulder.

Researchers now can create BECs in a laboratory and may be able to model some important qualities of objects that have befuddled cosmologists and astronomers for years. Like supernovae, neutron stars and black holes, BECs occupy a universe of extremes -- extreme gravitation, heat and energy.

Inside a neutron star for example, gravitation crunches most of its atoms -- which normally contain protons, neutrons and electrons -- into neutrons alone. Gravity goes to further extremes in a black hole, collapsing a star completely and preventing everything, even light, from escaping. Before stars collapse, they explode into brilliant supernovae that often take years to fade, all the while dominating their home galaxies.

On an infinitely smaller scale, BECs occupy an equally extreme environment. They exist at the coldest temperatures possible -- nearly absolute zero -- at which thousands of atoms can collapse like a neutron star into a single entity, a "superatom" so large it can actually be visible to the naked eye.

Cosmological models derived from BECs "may indeed yield some insight into how a real star works," Cornell explained.

One such insight might be the way black holes and neutron stars can rotate. Like these super-massive celestial bodies, BECs rotate "not as a rigid body like a bicycle wheel, but rather more like water swirling down a drain," Oglethorpe University physics professor Michael Rulison told UPI from Atlanta.

BECs also share a unique property with neutron stars -- superfluidity. Superfluids form only at extremely low temperatures approaching absolute zero. Then they flow without any friction, even slipping up the sides and out of an open container.

"Some fraction of the material in a neutron star is expected to be in the superfluid state," said NASA Jet Propulsion Laboratory physicist Donald Strayer in Pasadena, Calif. "The superfluid material in a neutron star must obey the same hydrodynamics equations as the material in a Bose-Einstein condensate cloud."

So under ideal conditions, BECs "provide an excellent laboratory for neutron star studies," Strayer said. But he cautioned neutron stars and other cosmological phenomena are too complex for researchers to recreate perfectly in laboratories.

"The conditions in a Bose-Einstein condensate, while similar to those in collapsed objects like neutron stars, are not identical," Rulison explained.

Wolfgang Ketterle, at the Massachusetts Institute of Technology in Cambridge, echoed the same reservations. Ketterle shared the 2001 Nobel Prize in Physics with Eric Cornell and Carl Wieman for their work with BECs.

"Some theorists spotted analogies for certain aspects shared by neutron stars and Bose-Einstein condensates, but I think people can overemphasize these analogies," Ketterle said.