A Two-Body Model of Matter and Quasi-Antimatter. Version 2.0

A phenomenological hypothesis inspired by a simple hydrodynamic analogy. This paper explores the possibility that spacetime may admit two geometric classes of gravitational sources, distinguished by a discrete parameter σ=±1\sigma=\pm1σ=±1, while preserving positive rest mass and positive energy density for all objects. Instead of introducing negative mass, the model proposes that quasi-antimatter (qAn) generates the opposite type of spacetime geometric response. Within the weak-field approximation, this naturally leads to repulsive interaction between matter and qAn, while quasi-matter (qM) shares the same geometric response as ordinary matter and is discussed as a possible analogue of dark matter. The work is deliberately phenomenological. It does not claim to provide a complete theory of gravity, but rather introduces a simple conceptual framework that may motivate further theoretical investigation and future experimental tests. The central idea originates from an unexpected source: the behavior of concave and convex menisci formed by ordinary objects floating in water. The paper asks a simple question: Could spacetime distinguish gravitational sources in an analogous geometric way? Follow my work and related discussions on Facebook: [Facebook] Keywords: General Relativity, Phenomenological Gravity, Modified Gravity, Dark Matter, Dark Energy