Eric Plaza

We present a revised assessment of Consistent Minimal Historical Gravity, a framework in which apparent galactic-scale gravitational anomalies are interpreted as a causal, historical response to local entropy production. The conceptual point of this paper is not that a massive scalar mediator produces a Yukawa falloff, which is standard in scalar–tensor effective theories, but rather that a causal, local, ghost-free historical-gravity embedding with entropy-production source Q ( x ) does not evade this generic Yukawa limitation. The covariant parent theory contains two scalar degrees of freedom, ϕ and χ , but in the static weak-field regime relevant for galactic phenomenology, it reduces to an effective single-mediator Yukawa closure generated by ϕ – χ mixing. The resulting extra acceleration therefore decays either exponentially for m χ > 0 or as r − 2 for m χ = 0 , and thus never reproduces the MOND-like asymptotic scaling Δ a ∝ 1 / r . We confront this minimal realization with an exploratory Bayesian Markov Chain Monte Carlo fit to a 153-galaxy working subset of the Spitzer Photometry and Accurate Rotation Curves (SPARC) catalogue, and we compare the inferred coupling scale with Solar System constraints. Within the universal-coupling closure adopted here, the SPARC-preferred region around α ≈ 5 × 10 − 3 lies entirely inside the Cassini-excluded region ( α < 1.15 × 10 − 5 ), which corresponds to a separation of approximately 2.6 decades in coupling strength. We therefore interpret this result as a no-go theorem for the minimal universal-coupling realization of entropy-sourced historical gravity, rather than as a blanket exclusion of environmentally screened or otherwise non-minimal historical-gravity scenarios.

The filling of microchannels represents a challenge from both the physical-mathematical and computational perspectives due to the inherent complexity of the phenomena involved, such as the solid–fluid interaction and inertial forces. In this paper, we propose a novel numerical approach to study the filling phenomenon and the dynamic of a fluid-air interface (front) advancement based on the smoothed particle hydrodynamics (SPH) method. We implemented a modified hydrostatic pressure within SPH simulations intended to generate an artificial fluid column that drives the fluid through the microchannels, thereby mimicking and controlling the microchannel filling process. The simulation results are successfully compared with an analytical model and experimental measurements, demonstrating that both experiments and simulations closely match the analytical solution. These findings highlight the robustness of the model and the experimental methodology employed while also demonstrating the ability of the SPH method to represent the pressure-driven filling phenomenon in microchannels realistically.

Smoothed Particle Hydrodynamics (SPH) has become a promising tool for the simulation of fluids. Although too much research has been addressed to improve the method over the years, a comparison of the errors and consistency evolution when trying different approaches are still necessary to define the best scheme for practical applications. Here, a two-dimensional Poiseuille flow test benchmark is employed to enforce comparisons when varying the kernel, the definition of the sound speed inthe pressure term, the viscosity and the Reynolds number.