A Self-Sustaining Anisotropic-Stress Shell in a Weak-Field Scalar–Manifold Model

In this work we developed and numerically studied a coupled scalar-field–plus–N-body system that generates a persistent, translating, shell-localized stress structure within a strictly weak-field gravitational surrogate. The inclusion of a higher-derivative field term produces anisotropic stress concentrated at the shell, leading to localized null-energy-condition proxy violation without negative energy density, a robust forward–backward optical-path asymmetry confirmed via eikonal ray tracing, and a self-maintaining, soliton-like configuration that persists under strong source ramp-down. Long-duration simulations demonstrate spectral stability, controllable shell thickness, and the ability to substantially suppress interior tidal distortion while preserving external asymmetry. Momentum audits show internal momentum exchange between masses and field, while centroid tracking reveals global drift arising from coupling to the computational domain, explicitly ruling out reactionless propulsion or true warp-spacetime behavior. The results therefore establish a stable anisotropic-stress manifold in an effective weak-field model with controlled propagation asymmetry and payload safety, while clarifying its limitations and non-equivalence to faster-than-light transport or physical warp drives.