The polarizable-vacuum (PV) approach to general relativity proposed by Puthoff (2002) 1 reformulates gravitational effects through a position-dependent vacuum dielectric constant K(x) in flat Minkowski space, with the velocity of light replaced by c/K throughout a special-relativistic Lagrangian. The approach has served as the theoretical substrate for an extensive subsequent literature on metric engineering, exotic propulsion concepts, and zero-point-field engineering 2–7.We examine the formulation’s status as a scalar theory of gravity and confront it with observational constraints accumulated since its 2002 publication. Three results follow. First, the PV formulation is mathematically equivalent to a specific class of scalar-tensor theory in the Brans–Dicke family, with the vacuum dielectric K mapping onto the Brans–Dicke scalar field Φ under coordinate transformation; the equivalence permits direct application of the no-go theorems and observational constraints established for scalar theories of gravity. Second, the post-2017 observational landscape — dominated by GW170817 propagation-speed bounds 8, LIGO–Virgo–KAGRA stochastic-background polarization-mode constraints 9, the Cassini PPN γ measurement 10, LARES-2 frame-dragging precision 11–13, and Event Horizon Telescope shadow imaging 14,15 — places severe constraints on PV in its 2002 form, with the propagation-speed and frame-dragging bounds in particular requiring fine-tuning that is unnatural in the original formulation. Third, the dual-charge framework of Sticco 16 addresses the same physical motivations as PV (vacuum-mediated gravitational effects, Maxwell-like dual structure, accessibility to engineering analogies) through a Bianchi-preserving source-side decomposition that survives the post-2017 constraints by construction and produces falsifiable predictions at the natural scale rmax ≈ 1.80 × 10 ¹⁸ derived⁻ from CODATA constants 17. The companion experimental sensitivity analysis 18 establishes the dual-charge framework’s engagement with the same observational channels that constrain PV. We argue that the dual-charge framework should be regarded as the conservation-respecting and observationally consistent successor to the PV programme.
Gene Sticco (Fri,) studied this question.