= Random-loss cooling of a Bose-Einstein condensate
{title2=$T\propto N^{2/5}$}
For a partially condensed equilibrium ideal <Bose gas> in a fixed three-dimensional box, the <energy> scales as $T^{5/2}$. Unbiased random particle removal keeps mean <energy> per particle fixed, so re-equilibration gives $T\propto N^{2/5}$ until condensation disappears. Removal of an excited particle can be followed by partial replenishment from the zero-energy condensate. This differs from selective <evaporative cooling of atoms>, which preferentially removes high-energy atoms and reduces mean <energy> per particle.
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