Structural Constraints on Physical Law Space and the Emergence of Observer-Compatible Universes

We investigate the structure of possible physical laws by explicitly exploring “law space”: the set of all internally consistent rule systems capable of generating coherent universes. Rather than varying parameters within predefined physics, we allow laws to emerge dynamically from a pre-law informational substrate devoid of spacetime, dimensionality, constants, or causal structure. Using an unconstrained generative framework filtered only by internal persistence, we identify discrete stability basins corresponding to distinct law regimes. We quantify basin structure, volume, and inter-basin relationships, and evaluate their capacity to support observers defined operationally by information persistence, memory continuity, self-modeling, and predictive capability. We find that observer-compatible universes occupy a highly constrained subset of law space characterized by stable causality, information conservation, and attractor-like emergent constants. Most conceivable laws collapse rapidly due to causal incoherence or entropy runaway. Cross-basin transitions generically destroy observer identity, with continuity preserved only under narrowly defined structural overlaps. These results suggest that observed physics is not arbitrary nor anthropically selected, but instead resides within a structurally privileged region of law space determined by observer viability constraints. The apparent fine-tuning of physical constants emerges naturally as an attractor phenomenon rather than a contingent coincidence.