72 Closer look at BEC Thermodynamically, this is a real phase transition, although unsual Pure quantum effect There are no real forces acting between the bosons, but there IS a real correlation in their motion caused by their identity (symmetrical wave functions) BEC has been so difficult to observe, because other (classical G/L or G/S) phase transitions set on much earlier BEC is a condensation in the momentum space , unlike the usual liquefaction of classical gases, which gives rise to droplets in the coordinate space.
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