Physical-variable field directions in world models are causally ablatable

Liu & Chen train small GRU, Transformer-lite and RSSM-lite transition models on a synthetic object-state prediction task (free-motion/collision/occlusion) [liu-chen-2026-event-conditioned-diagnostics] A 3-class linear probe classifies the physical-event regime at macro-F1=1.00 and a phase-aware field-readout probe on RSSM states reaches mean macro-F1=0.900, so kinematic/contact/permanence fields are overlapping probe-derived directions, not fixed subspaces [liu-chen-2026-event-conditioned-diagnostics] Projecting out the contact-aligned direction increases collision-window prediction loss in 6/6 architecture-seed cases (mean CFE 0.00319), beating random-direction, random-subspace and label-shuffle controls [liu-chen-2026-event-conditioned-diagnostics] Projecting out the object-permanence direction increases hard-occlusion loss (6/6 positive) but with a mixed margin against the random-subspace control, which the authors flag as more qualified [liu-chen-2026-event-conditioned-diagnostics]