  A gaseous Bose-Einstein condensate (BEC) offers an ideal testing ground for
studying symmetry breaking, because a trapped BEC system is in a mesoscopic
regime, and situations exist under which symmetry breaking may or may not
occur. Investigating this problem can explain why mean-field theories have been
so successful in elucidating gaseous BEC systems and when many-body effects
play a significant role. We substantiate these ideas in four distinct
situations: namely, soliton formation in attractive BECs, vortex nucleation in
rotating BECs, spontaneous magnetization in spinor BECs, and spin texture
formation in dipolar BECs.
