Framework Comparison — Ranked by Conceptual Similarity to DFD

Note: “Least-action optics” here refers precisely to Fermat’s Principle (δ∫n ds = 0), the variational foundation of geometric optics.

Rank Theory / Model Similarity Core Mechanism Relation to DFD
1 Density Field Dynamics (Alcock, 2024-2025) 100/100 ψ defines geometry & dynamics; n = eψ, a = (c²/2)∇ψ. Single scalar field replaces curvature; unifies light, matter, cosmology on flat ℝ³.
2 Fermat’s Principle (1662) 70/100 Light follows extremal optical path: δ∫n ds = 0. DFD generalizes the variational law via ψ setting n = eψ.
3 Einstein Variable-c Model (1911–1912) 65/100 c varies with potential; early optical gravity program. Conceptual ancestor; DFD completes with ψ-sourcing & matter coupling in one field.
4 Brans–Dicke Scalar–Tensor (1961) 45/100 Scalar φ modifies curvature (parameter ω). Shares “scalar gravity” flavor, but still inside GR curvature; DFD replaces it.
5 MOND / TeVeS (1983 / 2004) 40/100 Empirical low-accel scaling; TeVeS covariant version. DFD reproduces RAR/Tully–Fisher from μ(x)≈x (|∇ψ| regime) without tuning.
6 Emergent Gravity (Verlinde, 2016) 35/100 Entropic/holographic origin for gravity. Shares “no-DM” aim; mechanism statistical, not optical/variational.
7 River Model of Space (Hamilton & Lisle, 2008) 30/100 “Flowing space” coordinate picture within GR. Visual kinship only; DFD uses real optical phase flow (c₁ = e−ψ).
8 Gordon Optical Metric (1923) 25/100 Effective metric inside GR: gopt = g + (1−n−2)u⊗u. Analogy that depends on GR’s gμν; DFD is curvature-free and self-sourcing.
9 Eddington’s Optical Analogy (1919) 20/100 Heuristic refractive picture to illustrate GR lensing. Conceptual precursor only; no independent field/dynamics.
10 Tired-Light Hypothesis (Zwicky, 1929) 15/100 Photon energy loss over distance. No field equation or geometry; unrelated to ψ-based optics.
11 General Relativity (Einstein, 1915) 10/100 Gravitation = curvature of spacetime (gμν). Opposite ontology: curvature assumed vs ψ replacing curvature in DFD.

Summary: DFD (100) — ψ is the geometry. Fermat & Einstein 1911–12 (65–70) — direct conceptual precursors. Scalar / MOND / Verlinde (35–45) — partial phenomenology overlap, distinct ontology. Gordon / Eddington (20–25) — optical analogs within GR. GR itself (10) — curvature-first vs DFD’s ψ-first.