Polished Tunnel Dynamics (PTD): A Rigorous Scalar-Field Framework for Celestial Mechanics with Falsifiable Predictions Beyond General Relativity

Context. Polished Tunnel Dynamics (PTD) is a scalar field hypothesis proposing a pervasive cosmic scalar field Phi as a mechanistic substrate for gravitational phenomena, offered as an alternative to the geometric description of General Relativity. PTD is presented strictly as an untested, falsifiable hypothesis, not as an empirically confirmed theory.Methods. We construct a unified Lagrangian for Phi, incorporating a Yukawa fermion coupling, a dissipative viscous response derived from linear response theory, and a minimal variable speed of light correction bounded by existing literature constraints. From this Lagrangian we derive, in closed analytic form, the orbital dynamics of a test body, a modified radial acceleration relation, and an atmospheric confinement potential. We further derive, rather than estimate, the post Newtonian parameter gamma from the conformal coupling, and prove that the tensor mode speed equals c exactly, a structural consequence of the Lagrangian's Horndeski classification, yielding a closed form solar system bound and automatic consistency with the GW170817 gravitational wave speed constraint.Numerical verification. Except for the real SPARC fit described below, this study does not access external astronomical archives such as DESI, JPL ephemerides, or NRLMSISE 00. Every other quantitative result was produced by actually executing the Python code in the appendix against literature typical synthetic data, and is labelled a self consistency test rather than evidence that PTD describes the real universe. A hand written Metropolis Hastings sampler recovers the fabric viscosity scale from synthetic orbital data with clean convergence, while the fabric coupling g remains essentially unconstrained by a single year baseline, consistent with the framework's own prediction that fabric effects only become observable on multi gigayear or pulsar timing baselines. An information criterion computed on the same synthetic dataset favours the simpler Newtonian null, correctly reflecting that a one year orbital arc carries no power to distinguish PTD from Newtonian dynamics, precisely the falsifiability gap motivating the long baseline tests proposed in the roadmap.Real data test. One genuine empirical test was carried out: the public SPARC radial acceleration relation dataset, 2693 points from Lelli et al. 2017, was fit directly to the model equation, giving a critical acceleration of 1.152 times ten to the minus ten metres per second squared, with an intrinsic scatter of 0.082 dex and a reduced chi squared of 0.895, meeting the pre registered success criterion and matching literature values. An independent Bayesian posterior on the same real data confirms this with clean convergence. This is the paper's one substantive contact with real observational data; every other result remains a synthetic self consistency check.Falsifiable predictions. PTD's scientific content rests on three predictions with full operational protocols: a distance independent sunward acceleration for outer solar system spacecraft, termed the Shibah effect; a chromatic gravitational lensing signature testable with JWST NIRSpec; and sub centimetre periodic residuals in lunar laser ranging, each with explicit falsification criteria.Relativistic sector. Beyond gamma, the PPN parameter beta is derived from the same coupling ratio and found consistent, with no free parameter, with the real lunar laser ranging measurement. A working normalisation for the fabric density reduces three independent placeholders to two physical parameters, and the fermion selective Yukawa coupling is identified as a weak equivalence principle observable, correctly confronted with the real MICROSCOPE bound rather than the universal Cassini PPN framework. Two residual gaps, the proportionality constant linking fabric density to the field's vacuum value, and the link between the universal coupling and the non universal Yukawa coupling, are quantified explicitly: the two candidate normalisations differ by exactly a factor of four, and the Yukawa MICROSCOPE link is recast as a closed form fifth force constraint. These steps narrow, but do not close, the remaining milestone.Status. PTD remains an unconfirmed hypothesis. The radial acceleration fit is passed, but the framework's most distinctive claims, the Shibah effect, chromatic lensing, and tunnel spectroscopy, remain untested against real data, and two gaps remain open: a microphysical origin for the scalar field is not attempted, and no additional real dataset beyond SPARC is incorporated. Its value lies in the transparency of its derivations and the concreteness of its falsifiable predictions, not in any broader claim of observational support.