Quantum chill shows how cold stars stay in shape

By Richard Stenger
CNN.com Writer

(CNN) -- Cooling a cloud of atoms to almost absolute zero, scientists witnessed strange quantum effects of matter in an experiment that could lead to advances in our knowledge of the stars as well as our ability to reach them.

Rice University researchers used lasers to drop the temperature of a mixture of two types of lithium atoms to one-fourth of a millionth of a degree above absolute zero.

One group of the atomic particles shrank and the other stabilized during the cooling, a quantum condition that simulates the same process that keeps dense cold stars from completely collapsing under their own intense gravity, according to investigators.

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"This not only increases our understanding of the basic laws of nature, but also lays the foundation for the development of far-reaching technologies for deep space navigation," said Kathie Olsen of NASA, which funded the study.

Fermi pressure, named for the late Nobel physicist Enrico Fermi, refers to the theorized mechanism that stabilizes white dwarfs and neutron stars, which cool and become compact after they use their fuel.

The successful observation of Fermi pressure in the lab could lead to scientific advances in various fields, everything from atomic clock accuracy to digital communications to deep space navigation, the researchers said.

Lead investigator Randal Hullet and his colleagues hope to chill the gas even further to create a new type of super-liquid in which atoms may flow without friction.

The team said the experiment "gives clear experimental evidence for quantum degeneracy," a state of matter in which atoms behave like waves. So-called bosons and fermions were the two types of quantum particles involved in the study, which will be published in the March 30 issue of the journal Science.

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