Simulation Boundary Research (SBR), Volume II: Empirical Tests of Structural Boundary Fingerprints

Volume II of Simulation Boundary Research (SBR) empirically tests structural fingerprints defined and frozen upstream in Volume I. Six studies operationalize five fingerprint identities across astronomical and microphysical settings: Cosmic Microwave Background resolution fidelity, LIGO constraint-dominance switching, relativistic propagation, operational quantum speed limits, lattice string breaking, and unitarity-limited scattering. Each study separates the inherited structural target from its domain-specific measurement model, data, analytical procedure, calibration, robustness assessment, conventional explanations, and interpretation ceiling. The empirical outcomes are heterogeneous. The CMB study returns a bounded, sensitivity-limited non-detection of FP-011 in the evaluated representation. The LIGO study finds FP-004-consistent segmented-regime structure, but with material representation and model-form sensitivity and without identification of the underlying competing physical constraints. Relativistic Propagation supports FP-003 finite-upper-ceiling structure, Operational Quantum Speed Limits supports FP-002 lower-bound structure, Lattice String Breaking supports an FP-005-consistent finite-system regime transition, and Unitarity-Limited Scattering supports FP-003 finite-upper-ceiling shape structure conditional on the published observation model. :contentReference[oaicite:0]{index=0} None of these results requires non-standard physics. Conventional physical explanations remain sufficient or compatible within the tested scopes, and the detected structural relations do not by themselves establish unique computational mechanisms or simulation ontology. The value of the volume lies in bounded structural assessment, explicit treatment of sensitivity, representation, calibration and identifiability, and preservation of a traceable six-domain empirical record. :contentReference[oaicite:1]{index=1} Volume II does not aggregate the six studies into a common score, infer a shared physical mechanism, or establish that the universe is simulated. Whether any of the resulting empirical objects can support defensible cross-domain synthesis is reserved to Volume III. :contentReference[oaicite:2]{index=2} This work is independent private research conducted with extensive AI-assisted research support under the final scientific and authorial responsibility of Thomas Johannes Schultheiss.