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Re: BEC

Jim Green asked:
Folks, are the Boise-Einstein *statistice* found in the usual thermo text
sufficient to explain the recently reported Boise-Einstein *condensation*.

I think the best answer to your question is "yes" *and* "no". The Bose-
Einstein condensation seen in these experiments is quite close to the simple
textbook explanation given for a hypothetical ideal boson gas. The experiments
are much closer to the ideal gas (with quantum boson statistics) then the other
previous cases of macroscopic occupation of a single quantum single-particle
state for other phenomena. The other cases of superfluidity in 4He and of
Cooper pairs in superconductors are condensations involving systems with
*significan* interactions between the degrees of freedom. After all,
superfluid 4He forms in a background of *liquid* He not an ideal gas of He.
In these recent experiments the condensation is observed in a very dilute
(noninteracting/ideal) gas phase as in the textbook example. The new
experiments are still not perfect examples of the phenonmenon of *pure* Bose-
Einstein condensation because they are for such small samples (of only
thousands of particles rather than moles of particles) that they do not go
very close to the thermodynamic limit, and also, the magnetic traps which
contain the samples places the samples in a complicated external potential
that has to be considered when explaning the system's behavior. The boundary
conditions are considerably more complicated than an ideal hard-wall box with
no potential inside.

David Bowman
dbowman@gtc.georgetown.ky.us