UNIFICATION 0 - A Shared Lightlike Boundary for Relativity and Quantum Theory

This work introduces the Chi Framework as a compact structural interpretation of the shared lightlike boundary between relativistic and quantum descriptions.On the relativistic side, the massless boundary is defined by the standard relation E = pc. On the quantum side, using the standard Planck–de Broglie relations E = ℏω and p = ℏk, the same boundary yields ω = kc. This common limit motivates the introduction of the dimensionless boundary parameter χ = pc/E = kc/ω = v/c, together with the corresponding deviation parameter δ = 1 − χ².These parameters provide a compact structural language that organizes several familiar relativistic quantities, including the Lorentz factor, proper time, and mass-shell deviation, while also admitting a phase-based interpretation.The present work is intentionally limited in scope. It introduces no new equations of motion, proposes no modification to established relativity or quantum mechanics, and makes no empirical claims beyond known physics. Its purpose is interpretive and structural: to identify a shared invariant boundary principle through which familiar relativistic and quantum expressions may be organized within a single limiting framework.This paper is the first in the UNIFICATION series. Subsequent papers explore phase amplification, coupled zero-like and infinity-like limits, geometric interpretation, field-based formulations, and candidate governing equations. An, included, educational companion text, UNIFICATION: The Chi Framework — Eight Lessons on the Boundary Between Relativity and Quantum Mechanics, is a textbook which anybody with at least a highschool level of accomplishment can understand. Currently Available: UNIFICATION 0 - A Shared Lightlike Boundary for Relativity and Quantum Theory - v1.00 https://doi.org/10.5281/zenodo.19860494 UNIFICATION I - Phase Structure and the Lightlike Boundary - v1.00 https://doi.org/10.5281/zenodo.19862660 UNIFICATION II - Implications of the Lightlike Boundary and Phase Structure - v1.00 https://doi.org/10.5281/zenodo.19863301 UNIFICATION III - Toward a Dynamical Formulation of the Lightlike Boundary Framework - v1.00 https://doi.org/10.5281/zenodo.19895578 UNIFICATION IV - Consequences and Implications of the Chi Framework - v1.00 https://doi.org/10.5281/zenodo.19896296 UNIFICATION V - Concerning the Current Absence of a Governing Equation for the Chi Framework - v1.00 https://doi.org/10.5281/zenodo.19921182 UNIFICATION VI: The Chi Boundary Method and Structural Invariants - v1.00 https://doi.org/10.5281/zenodo.19925550 UNIFICATION VII - A BOUNDED UNIVERSE 0 - Reciprocal Boundary Structure and the Reinterpretation of Zero and Infinity https://doi.org/10.5281/zenodo.20090590 UNIFICATION VIII - A BOUNDED UNIVERSE I - Math of Counting vs a New Zed/Irony Math - v1.01 https://doi.org/10.5281/zenodo.20128424 UNIFICATION IX - A BOUNDED UNIVERSE II - Toward a Bounded Interpretation of Relativistic Extremes - v1.00 https://doi.org/10.5281/zenodo.20160715 UNIFICATION X - A BOUNDED UNIVERSE III - Reciprocal Discernment and the Quantum Boundary - v1.00 https://doi.org/10.5281/zenodo.20171582 UNIFICATION - The Chi Framework - Eight Lessons on the Boundary Between Relativity and Quantum Mechanics - v1.00 https://doi.org/10.5281/zenodo.19863601 A public project archive containing all PDFs in the UNIFICATION series is also available through the Open Science Framework (OSF): UNIFICATION SERIES: https://osf.io/mpvgj/files/osfstorage/