2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/151941The Bogoliubov approximation and the Gross-Pitaevskii equation characterize the effect of repulsive interactions on a dilute ideal Bose-Einstein gas in a spherical harmonic trap. For large $N$, the interactions expand the condensate relative to an ideal Bose gas; both the speed of sound and critical angular velocity $Ω_{c1}$ for creation of a quantized vortex depend crucially on the interparticle repulsion through the coherence length $ξ$.6 pages, latex, no figures, to appear in Proceedings of Ninth International Conference on Recent Progress in Many Body Theories, Sydney, July, 1997Statistical Mechanicstext