Forces of Nature, featuring Sandra Bullock and Ben Affleck as star-crossed lovers, is the cinematic equivalent of Styrofoam: a weightless romantic comedy of synthetic feelings. Affleck plays Ben, a straight arrow on his way from New York to Savannah, Georgia, to marry his fiance, Bridget (Maura Tierney). Then his plane skids off the runway, and the free-spirited Sarah (Bullock) - a fellow passenger - skids into his life. You probably know where this is headed. Though Ben and Sarah try various