One Equation. One Density. From Domain Boundary to Flat Rotation Curves.

What this simulator is and what it is trying to show

For decades, the standard explanation for why galaxies rotate faster at their outer edges than baryonic matter alone can account for has been dark matter — an invisible mass component fitted separately to each galaxy. No dark matter particle has ever been detected. The fitting is not a prediction; it is curve fitting with a free parameter per galaxy.

Big Flare-Up Theory (BFUT) gives a physical explanation without dark matter particles. The Spaticle field — the physical substrate of space — has a non-zero equilibrium density ρ_s = 5.9 × 10⁻²⁷ kg/m³. This single number does three things at once:

• It sets the finite gravitational domain of every mass via the DD1 relation R = (3M / 8π ρ_s)^(1/3). Gravity is not infinite range. Every body has a boundary beyond which its gravitational influence ends.
• It determines whether a rotating galaxy sustains a coherent substrate deformation domain — the physical mechanism that produces flat rotation curves — through the DD1 coherence index I_DD1.
• It predicts the galaxy rotation curve directly: the substrate provides extra gravitational support at large radii through organised rotational entrainment, replacing the dark matter halo entirely.

The DD1 coherence index formula is: I_DD1 = v × R_core / (K_DD1 × R_gal^0.9), where v is the galaxy's rotation velocity, R_core is the radius of its coherently rotating central region, R_gal is its total observed extent, and K_DD1 = 9 km/s kpc^0.1 is a single constant fixed once on the SPARC dataset and never adjusted per galaxy. If I_DD1 ≥ 1, the galaxy sustains a coherent domain and shows a flat rotation curve. If I_DD1 < 1, it does not — and it will appear dark-matter-deficient. This is not a missing particle. It is a coherence failure: insufficient organised rotation to entrain the Spaticle substrate.

GR assumes gravity has infinite range. At particle scales this produces absurd results — the proton's gravitational influence would extend forever, which is visibly wrong. At cosmic scales GR appears to work because everything we have ever measured sits within nested domain structures. We have never observed anything outside a domain boundary, so GR's infinite-range assumption has never been falsified observationally. BFUT fixes this at every scale with ρ_s.

This simulator covers the work of Paper P18 (Beyond General Relativity) and Paper P25 (The Spaticle Field as the Physical Identification of Dark Matter). Both papers use the same DD1 framework and the same ρ_s. P18 derives the gravitational carrier dynamics and validates DD1 across 190 systems. P25 demonstrates that the Spaticle field satisfies every operational property historically attributed to dark matter, across six independent physical sectors, all converging on the same ρ_s.

How to use this simulator: Select any of the preset bodies below to see their domain boundary, coherence index, and rotation curve computed instantly from the paper's verified parameters. All preset values are locked — they reproduce the paper's results exactly. If you want to explore how changing the parameters affects the physics, select Custom — this unlocks all sliders so you can vary v, R_core, R_gal, mass, and other inputs and watch the coherence index and rotation curve update in real time.