Measurement Attributes — Atomic Interface: The Measurement Boundary Between Rule System and Velocity System

This paper takes the atom as an interface and distinguishes two physical systems: the rule system inside the atom and the velocity system between atoms. In the rule system, the orbital radius determines the electron velocity, the energy level structure constitutes the measurement rule wall, the system cannot measure its own measurement reference from within, and external observation is merely its manifestation and projection in macroscopic space. In the velocity system, electrons move between atoms, and pressure affects electrical resistance by altering lattice spacing, phonon scattering, and relaxation time τ, but does not reach the internal rule system of the atom. This paper argues that pressure acts on the velocity system while frequency/light acts on the rule system; the two belong to different measurement systems, and cross-system measurement relations occur only at the interface. The Coulomb force dominates inside the atom, where gravity is negligible at the atomic scale; however, because the Coulomb force tends toward zero in macroscopic accumulation due to charge neutrality cancellation, conductor shielding, and net charge instability, while gravity grows linearly due to the absence of any cancellation mechanism, the two curves must inevitably cross — after the crossing, gravity surpasses the Coulomb force and becomes dominant. Under extreme high pressure, gravity may breach the boundary of the rule system, triggering a qualitative change in the data line. This paper uses existing experimental data (Bohr energy levels, Franck-Hertz experiment, piezoresistive effect) to support the system division. It does not propose a new theory but rather uses the measurement interface distinction framework to re-interpret existing physical structures and experimental data.