Layered equivalence

The enrichment ladder changes what “the same” can mean. At E_0, sameness is identity of generated objects, addresses, and normal forms. At E_1, physics introduces physical-kind equivalence: two distinct carrier realizations count as the same particle or mode when they preserve the same defect-bundle, holonomy, charge, mass, spin, and transport invariants under admissible readout. Thus “this is a neutron” does not assert numerical identity of substrate pieces; it asserts membership in the neutron equivalence class. Higher-layer analogues – code equivalence at E_2, semantic/proof equivalence at E_3 – appear below as the construction continues into Books VI – VII.