Of Superfluids and Quark Stars
Researchers at Rice University have managed to achieve superfluidity with supercooled fermions in the lab. Fermions are the fundamental particles that constitute matter, coming as leptons and quarks, and having half-integer spins. (While Bosons are the particles that mediate the forces, such as photons, W vector, gluons and gravitons, and have integer spins.) There are of course, the composite particles that come as fermions or bosons -- without getting into a long explanation that I would probably screw up, let's just say it's all about the total spin of the particles and leave it as that. Full integer spin means a particle is a boson -- half integer spin means it's a fermion. In this case, the researchers used lithium-6 atoms -- fermions.
When cooled to near absolute zero, it has been predicted that fermions with equal but opposite spins would attract each other, forming pairs and behaving like a single particle. This change of phase allows superfluidity and superconductivity to occur.
In a superfluid, occurring in materials that are not electrically charged, there is zero viscosity, zero entropy and infinite thermal conductivity. While in a superconductor, in materials carrying an electrical charge, electrons can traverse the material without interacting with it -- there is no electrical resistance, and no interior magnetic field (you've probably seen the cool experiments where a magnet levitates due to this property). What is most interesting in this experiment, is that the researchers allowed the fermionic pairing to be unbalanced -- thus leaving some particles unpaired. Remarkably, the lithium-6 gas behaved just as would be expected if there was a complete pairing of fermions. This goes a step beyond what an MIT team had accomplished earlier this year.
What does this all mean? Who knows. It's nothing that's ready to have real world applications, but it does provide a platform for further studying of superfluids and superconductors. There is also speculation that the results from this experiment present the type of exotic matter found larger neutron stars, known as quark stars.
When cooled to near absolute zero, it has been predicted that fermions with equal but opposite spins would attract each other, forming pairs and behaving like a single particle. This change of phase allows superfluidity and superconductivity to occur.
In a superfluid, occurring in materials that are not electrically charged, there is zero viscosity, zero entropy and infinite thermal conductivity. While in a superconductor, in materials carrying an electrical charge, electrons can traverse the material without interacting with it -- there is no electrical resistance, and no interior magnetic field (you've probably seen the cool experiments where a magnet levitates due to this property). What is most interesting in this experiment, is that the researchers allowed the fermionic pairing to be unbalanced -- thus leaving some particles unpaired. Remarkably, the lithium-6 gas behaved just as would be expected if there was a complete pairing of fermions. This goes a step beyond what an MIT team had accomplished earlier this year.
What does this all mean? Who knows. It's nothing that's ready to have real world applications, but it does provide a platform for further studying of superfluids and superconductors. There is also speculation that the results from this experiment present the type of exotic matter found larger neutron stars, known as quark stars.
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