Friday, March 26, 2004

Star Geek: The Next Generation

All right class, how many states of matter are there?

Three! Solids, liquids, and gases. Just like we all learned in school.

Except actually there are four. Plasma is an extremely energetic state of matter where atoms have been ripped apart into ions and free electrons. Stars are plasma.

Whoops, I'm sorry, there are five. The strange form called a Bose-Einstein condensate only exists at extremely low temperatures, when members of a class of particles called bosons start to act as if they were one big particle which has a number of strange properties, including that light travels through it very slowly.

Oh, darn, sorry again. There are now six.

The partner to the group of particles called bosons is the group consisting of fermions. And scientists have now formed fermionic condensates - a type of matter so new that most of its basic properties are unknown. They're very cold and probably have zero viscosity (that is, absolutely no resistance to flow). Beyond that is the unknown.

The trick in making such a condensate is that fermions are, if you will, unsociable. They tend to repel each other - unlike bosons, which join easily. A finely-tuned magnetic field was used to get around that to build up a condensate.

So what? Well, because such condensates may be "superfluids," they might tell researchers a lot about a related phenomenon: superconductivity, in which electricity flows with zero (or at least near-zero) resistance. Long offering dreams of incredibly efficient electricity generation, superfast computers that would make today's supercomputers seem like Model Ts, and more, the warmest temperature at which any material now displays superconductivity is, unfortunately, a chilly -135 degrees Celsius. Rather impractical.

But "the strength of pairing in our fermionic condensate, adjusted for mass and density, would correspond to a room-temperature superconductor," notes [lead researcher] Jin. "This makes me optimistic that the fundamental physics we learn through fermionic condensates will help others design more practical superconducting materials."

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