Structural Admissibility of Passive Expansion under Compression in Solid-State Material Systems

DESCRIPTION This work establishes structural prior art for solid-state material systems that exhibit macroscopic expansion under compressive loading. Without disclosing implementations, it identifies invariant conditions necessary for admissibility of passive negative compressibility, reframing “impossible” behaviors as outcomes of admissible internal structure. The paper is non-constructive and non-enabling, intended to delimit the causal envelope of such systems and prevent over-broad patent claims while preserving open research.