A Black-Hole-Matter Hypothesis for Spacetime Geometry, Energy and Particles: The Börekci-2 Node-Spacing Metric, Literature Basis and Experimental Constraints

Preprint of a manuscript submitted to the International Journal of Theoretical Physics (Springer) on 24 September 2026; not yet peer reviewed. This hypothesis: Börekci’s Hypothesis of Black-Hole Matter as the Primary Substance of the Universe. A conceptual hypothesis is presented that defines spacetime geometry as a structure made of black-hole matter joined by special links, mobile and changing according to the gravity and energy within it, and proposes this matter as the primary substance of all spacetime-fabric geometry, energy, atoms and subatomic particles. Four propositions are stated (P1–P4). The literature basis is compiled, including experiments showing that the quantum vacuum is not empty (notably the 2026 STAR virtual-quark-pair spin correlation), emergent-spacetime theories, models relating black-hole interiors to the vacuum, and work connecting black holes to the origin of the universe. A node-spacing relation is derived from a constant-proper-spacing postulate, spacetime curvature around the Sun, Earth and Moon is computed with five measures, and a node-spacing metric (the Börekci-2 metric) is defined; it is identical to the Schwarzschild geometry outside the horizon, reproduces GPS and S2-star time dilation, and yields natural markers for the horizon, photon sphere, ISCO and the black-hole-matter surface. The equivalence principle is preserved at the network level and atomic-clock constraints are satisfied. Two distinguishing predictions are given: a transition region at the event horizon, and a blue tilt of the primordial gravitational-wave spectrum from an early stiff-fluid era. The hypothesis is consistent with, but not proven by, the literature; the steps required for a full test are stated. Supplementary file: animated video summary of the paper in English (Borekci_Hypothesis_Black_Hole_Matter_EN_v2.mp4, 3 min 49 s), with narration and subtitles. The visualisations are schematic scientific illustrations; the black-hole image is an artistic rendering, not a ray-traced simulation.