This 1992 release is a black diamond of a film, hard-edged and compelling. Volatile, verbal and streetwise, it neither complains or explains--it simply puts a world on display and dares you to be indifferent to it. Set among the petty hoodlums and junior-grade hard guys of Brooklyn's Green Point section, the debut feature of writer-director Nick Gomez is independent American filmmaking at its best. The center of "Gravity" is Jimmy (Peter Greene, pictured with Edie Falco, who plays his wife Denise). Jimmy is a small-time street outlaw who, though horrified at the thought of actual work, is stable by local standards. His pal Jon (Adam Trese) is the original hothead, and into their edgy friendship comes the sinister Frankie (Paul Schulze), just back from Florida in a stolen car with a trunk full of illegal firearms (Showtime Tuesday at 12:35 a.m.).