This paper derives the QGD account of antimatter and particle-antiparticle annihilation from first principles, without introducing new ontological categories or force laws. Within Quantum-Geometry Dynamics (QGD), a particle and its antiparticle are preon(+) aggregates of equal mass whose internal momentum structures are exact mirror images: for every constituent preon(+) propagating in direction p̂ within the particle, there is a corresponding preon(+) propagating in direction −p̂ within the antiparticle. This mirror-image relationship is not a label or a conserved quantum number — it is a structural geometric consequence of the p-gravity binding condition. The electromagnetic attraction between a particle and its antiparticle — arising from their opposite polarisation geometries in the free-preon(+) background — draws them together. At separation below the minimum volume threshold volmin established in P11, Chapter 11, the intervening preonic space is too small to contain sufficient free preons(+) for electromagnetic polarisation to operate. Electromagnetism is geometrically nullified. P-gravity, distance-independent and requiring no medium, acts unopposed at near-zero preonic separation and is orders of magnitude stronger than at nuclear scales; it forces the two structures to merge. Within the merged structure, every preon(+) drawn from the particle meets a corresponding preon(+) from the antiparticle propagating at θ = 180° — the binding condition G⁺(a;b) ≥ Pc · cos θ is maximally violated across the entire population simultaneously. No equilibrium configuration exists. Strict causality forces immediate resolution: the preons(+) self-sort by trajectory direction under p-gravity, grouping into parallel-momentum streams — photons — which are the unique stable p-gravity bound configuration available to preons(+) that cannot satisfy the binding condition with antiparallel neighbours. Momentum conservation is automatic: the mirror-image structure guarantees that the emitted photons carry equal and opposite total momenta. The entire account — the structural definition of antiparticle, the force-sequence of the approach, the mechanism of merger, and the necessity of photon emission — follows from the p-gravity binding condition, the volmin threshold, and strict causality already established in P11. No new mechanisms are introduced.
Daniel Burnstein (Sun,) studied this question.