The Fundamental Speed Theory (FST): A Unified Vector Field Framework for Dark Matter, Baryogenesis, and Gravitational Lensing

This paper introduces the Fundamental Speed Theory (FST), a novel paradigm that posits motion itself as a fundamental entity of nature, described by a dynamic four-vector field V^{\mu} coupled to spacetime geometry. FST provides a unified framework to address cosmic phenomena, primarily attributed to dark matter, without requiring its existence. The theory's core strength lies in a nonlinear screening mechanism, allowing it to: · Achieve a superior fit to galactic rotation curves, with a \chi^{2}/{\rm dof}=1.08 across 175 SPARC galaxies, outperforming standard \LambdaCDM (1.15) and MOND (1.22) models.· Maintain exact agreement with stringent solar system tests (e.g., light deflection, time delay).· Generate unique, falsifiable predictions that distinguish it from dark matter, including an extra polarization mode in gravitational waves and cored density profiles in dwarf spheroidal galaxies. FST presents a mathematically consistent, empirically successful alternative to the standard cosmological model, with testable predictions accessible to current and next-generation experiments. Keywords: Modified Gravity, Dark Matter, Galactic Dynamics, Fundamental Physics, Vector Field Theory, Screening Mechanism, Rotation Curves, SPARC, Gravitational Waves, Cosmology.