Brendan Healy's two-act comedy about a haughty couple arguing at their engagement party while the caterers flirt with or pine for the guests compares matters of the heart and scientific theories. The first act is stilted and artificial as it tackles esoteric topics and human relations; the second concentrates on the characters' loneliness and winds up being both more human and more humorous. The director of this world-premiere production, Daniel Shea, has a light touch, and the cast members, particularly Robyn Coffin and Tom Weber, manage to make their characters sympathetic. But the play's dark lectures on history and physics need to be in better sync with its emotional side. Through 8/20: Thu-Sat 8 PM, Sun 3 PM. Athenaeum Theatre, third-floor studio theater, 2936 N. Southport, 312-902-1500. $15-$18.