A Chosen Future Can Still Be Rewritten: Causal Writability in Video Models
Study shows video models often learn correct physics but fail to use it; low-dimensional 'causal writability' edits can restore correct motion.
The paper demonstrates 'causal writability' in video generation models: physically correct motion remains available inside the model even when the model outputs incorrect motion. In a red/blue mass oscillation setup, a low-dimensional edit predicted from simple physical variables restores correct fast motion, with a sharp depth boundary marking commitment. Early causal writability predicts which training errors later get corrected, and both writability and closure reproduce in a pretrained 1.3B video model.