Observer First Physics

This work establishes a minimal, physically grounded definition of an observer—finite, local, interaction-driven, and relational—and shows that from these conditions alone, the core structures of physics necessarily follow. Quantum mechanics (Hilbert space, linearity, Born rule, no-cloning, uncertainty), thermodynamics (the second law, Landauer’s principle), and relativistic causality (finite invariant propagation speed) are not postulated but emerge as unavoidable consequences of what it means for a system to record interactions. The result is a single constraint: any universe capable of containing such observers must exhibit these structures and properties, including non-equilibrium conditions, stable bound states, finite signal speed, and a compatible spacetime dimensionality. Physics, in this framework, is not a collection of independent laws but the unique coherent description of observer-compatible reality.