Showing our work
How we checked the physics.
Every scene on this site says what is calculated and what is chosen to tell the story. This page shows the checks behind the calculated parts: what each one compares against, and the result.
Feed the Black Hole
Pieces fall under the Paczyński–Wiita gravity of a still black hole, or, with spin, the Artemova–Björnsson–Novikov form plus Lense–Thirring frame dragging. These are simpler than full general relativity, but the checks below show where they land exactly on its numbers. Others test the stepping, the breakup rules, the mergers, and the light tracer that draws the sky, run outside the graphics card with exactly the same steps as the page.
20 of 20 pass · last run 2026-10-17
| Check | Our result | Expected | Compared with | |
|---|---|---|---|---|
| Innermost stable orbit Closest a piece can circle without falling in | 3 | 3 | Pass | Schwarzschild: 6GM/c² = 3 rs |
| Innermost bound orbit Closest orbit that is only just held | 2 | 2 | Pass | Schwarzschild: 4GM/c² = 2 rs |
| Capture limit Below this angular momentum, anything falling from far away is swallowed | 2 | 2 | Pass | Schwarzschild: 4GM/c |
| Capture test (integrator) A piece at 98.5% of the limit is swallowed; at 101.5% it swings back out | swallowed / escaped | Pass | Limit 2 rs c | |
| Swallowed or not Predicted fate (swallowed, orbiting, escaping) matches a step-by-step simulation for 200 random throws | 200 of 200 | Pass | Effective-potential barrier | |
| Closest approach Integrator vs exact closest approach for a chosen aim | 6.00006 | 6 | Pass | L² = rp²/(rp − 1) |
| Orbit stays put Radius after 50 circular orbits at 10 rs | 10.0002 | 10 | Pass | Energy-conserving stepping |
| Hills mass for the Sun Hole mass above which the Sun falls in whole | 114331000 | 100000000 | Pass | Hills 1975: about 10⁸ Suns |
| Half the star stays Share of a torn-apart Sun that is still bound to the hole | 0.503 | 0.5 | Pass | Frozen-in approximation (Rees 1988) |
| Chirp length Time from 35 Hz to merger for the first detected black-hole pair | 0.158775 | 0.2 | Pass | LIGO 2016: about 0.2 s (leading-order formula) |
| Energy radiated Share of the total mass turned into gravitational waves | 0.0478541 | 0.0468278 | Pass | LIGO GWTC: 3.1 of 66.2 Suns |
| Final spin Spin of the merged hole | 0.683767 | 0.69 | Pass | LIGO GWTC: 0.69 |
| Inspiral Separation after the predicted time (should reach 3 rs) | 3.00088 | 3 | Pass | Peters 1964 |
| Atoms pulled apart Tidal pull across an atom equals the electron’s binding at this depth | 9.04422e+22 | 9.04422e+22 | Pass | Coulomb binding at the Bohr radius |
| Spinning edge Edge of a hole spinning at 90% of the maximum | 0.717945 | 0.717945 | Pass | Kerr horizon M(1 + √(1 − a²)) |
| Spinning closest orbit Closest stable orbit, turning with the spin, at 90% spin | 1.16045 | 1.16044 | Pass | Bardeen, Press & Teukolsky 1972: 2.3209 M |
| Frame dragging How far a polar orbit’s plane turns in 40 orbits at 60 rs, 90% spin (radians) | 0.342831 | 0.34287 | Pass | Lense & Thirring 1918: Ω = 2J/r³ |
| Pair spiralling in Separation of two holes after Peters’ predicted time to reach 12 (in rs of the first hole) | 12.0003 | 12 | Pass | Peters 1964 |
| Shadow edge Size of the black shadow in the sky tracer (impact parameter, rs) | 2.59808 | 2.59808 | Pass | Schwarzschild photon sphere: √27/2 rs |
| Light bending far out Bending of light passing 400 rs from the hole (radians) | 0.00501485 | 0.00501841 | Pass | Einstein: 2rs/b, plus the next term |
Distances are in units of the edge’s distance from the centre (the Schwarzschild radius, rs); angular momentum in rs × light speed. The “half the star stays” check uses random sampling, so its last digits vary from run to run.
The other experiences
Event Horizon
Every pixel’s light path is stepped numerically through the Schwarzschild (still) or Kerr (spinning) solution. The disk’s brightness and temperature are chosen; its motion, Doppler shift and redshift are calculated. A visualization, not a forecast for a real system.
Probe Experiments
17 model checks pass, including analytic capture limits, circular-orbit clocks and mirrored spins. Seven trajectories were cross-checked against a separately written solver (Hamiltonian equations, SciPy’s DOP853 integrator).
Star Encounters
16 model checks pass, including finite results across 112 star, hole and depth combinations, debris energies, fallback timing and direct capture by large holes.
The Recomposition and The Plunge
At zero spin the Recomposition’s 2,400 orbits reproduce the still-hole calculation. The tidal-stretch formula is checked against an independent numerical integration of the tidal equations.
What is not checked yet
- No independent scientist has reviewed the site.
- Speed has been measured on emulated phones and software graphics, not yet on a range of real phones.
- Feed the Black Hole ignores the pull of the pieces on each other and light-travel time. With spin, the pieces’ gravity is an approximation near the hole (the checks show where it is exact), and debris behind the hole is bent as if it were not spinning. Debris settling into a disk runs at a chosen, sped-up rate.
- With three or four black holes, their pull on each other is Newtonian with gravitational-wave drag added, not full relativity.
- Bending of light by two black holes at once is approximated by adding up each one’s bending.
Found something wrong? That is the point of showing the work. The physics code is published unminified with the site (for example feed-model.js).