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Re: BEC



Hi Jim-
In response to:
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A question I have is whether BEC can occur for a situation of a small number
of energy levels -- say 2, 3, 4 or so -- or whether the ground state must be
a member of a large continuum of levels. The ground atate being where
everything ends up. (:-)
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I don't think the question is well-posed. I can't imagine a
many-particle system "with only a small number of energy levels". But
I'll try to read your mind and offer the following:
Imagine a gas of non-interacting Bose particles in a box. The single
particle spectrum is discrete and is determined by the boundary conditions
at the ends of the box. Bose-Einstein condensation occurs when the box is
cooled sufficiently for many of the particles to end up in the ground state
of the system. That, in fact, is the definition of "Bose-Einstein
condensation".
The particles occupying the ground state occupy zero volume, and
an isotherm on a p-v diagram is a horizontal line. For further details,
see the rather nice article in Brittanica.
Regards,
Jack