What this exhibit models × Light follows curved paths The view numerically traces rays backward from your camera using the Schwarzschild null-geodesic orbit equation in a Cartesian representation. Rays either cross a thin disk, escape to a procedural star field, or enter the horizon. Multiple disk images arise from the traced paths. This is a real-time approximation with finite step size, not a research-grade image.
Spin has a carefully defined role Spin moves the disk's inner edge using the prograde Kerr ISCO formula and changes its orbital period using the Kerr circular-orbit formula. The light propagation and capture boundary remain Schwarzschild: frame dragging, the spin-dependent shadow, and full Kerr redshift are not solved. Spin is limited to 0.9. The “more physically realistic” mode adds approximate gravitational redshift and stronger relativistic Doppler beaming, uses a thin opaque disk, and removes teaching labels. Both modes use illustrative warm colors and artistic gas texture; neither is a literal visible-light photograph or a full plasma simulation.
Mass, clocks, and brightness Lengths are in gravitational radii, GM/c². Increasing mass scales the physical size and all orbital times linearly. The camera distance scales with mass, and playback uses normalized time so every mass remains explorable. Brightness scales emitted light only; it does not solve how gas supply changes the disk. “1 exhibit second” includes your playback speed. Pausing stops disk evolution; your camera remains interactive.
The photon experiment Its trajectory uses the same Schwarzschild orbit equation, integrated with fourth-order Runge–Kutta. The beam starts far away, and the exact critical impact parameter from infinity is 3√3 GM/c², or about 2.598076 Rₛ. Near-critical paths are sensitive to finite precision. The animated dot shows path progress, not a distant observer's clock.
Explore the science NASA: Black Hole Accretion Disk Visualization NASA: Anatomy of a black hole Photon spheres and the Schwarzschild radius