Radius r / r_s-

Faller's clock τ-

Far clock t-

Tidal stretch-

horizon r_sphoton sphere 1.5 r_sISCO 3 r_s

Tidal stretch
(exaggerated shape)-

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What happens if you fall into a black hole?

Blender 5.2 modelsThree.js r160Schwarzschild (non-rotating)classical GR

Drop a probe from rest toward a non-rotating black hole. Its own clock reaches the singularity in a finite time, but a distant observer never sees it cross the horizon. Tidal forces stretch the body: lethal outside a stellar-mass hole, harmless at the horizon of a giant one. Switch between the two observers and watch light bend around the shadow.

Presets

Black hole and fall

Mass (solar masses, log scale)

Starting radius, at rest (in r_s, log scale)

Body length for the tidal readout

Live readouts

Experiment: does the mass decide if you survive the horizon?

Same fall from rest at the horizon, five black holes. Proper time to the singularity is measured by integrating the equation of motion and compared with πr_s/(2c); the stretch across your body at the horizon decides whether tides already tore you apart outside it. Stress marker used here: a 10 g head-to-foot difference (illustrative, not medical).

Independent numerical checks (live)

View

mark horizon / photon sphere / ISCO (distant view) tidal-stretch inset

Whole fall lasts

Drag to look around (or orbit in the distant view), wheel or pinch to zoom. The playback runs in equal steps of the cycloid angle, so it lingers near the start and slows again near the singularity.

The science

Model. Schwarzschild metric of a non-rotating, uncharged hole of mass M. Horizon radius r_s = 2GM/c² = 2.95 km × (M/M_☉).

free fall from rest at r0: d²r/dτ² = -GM/r² r = (r0/2)(1+cosη), τ = (r0/2)√(r0/r_s)(r_s/c)(η+sinη) to the singularity (η=π): τ = (π/2)(r0/r_s)^1.5 r_s/c

Two clocks. A far observer's coordinate time obeys dt/dτ = E/(1-r_s/r) with E = √(1-r_s/r0). It grows without bound as r → r_s, so the faller never seems to cross; light from it is also redshifted by f/(E+√(E²-f)), f = 1-r_s/r, and fades. The faller's own clock is perfectly regular and crosses the horizon after a finite proper time, then hits the singularity at most πr_s/(2c) later (for a 10 solar-mass hole about 155 µs, for 4 billion solar masses about 17 hours).

Tides. For radial infall the stretch between two points a distance L apart along the fall is exactly 2GM L/r³ in the falling frame (the sideways compression is half of that). At the horizon it equals c²L/r_s², so it falls as 1/M²: lethal for stellar holes, mild for supermassive ones. The picture in the inset exaggerates the shape: real elongation is tiny at first, then tears matter apart.

Light. Photons follow u'' = -u + (3/2)u², u = r_s/r, φ the angle in the orbital plane. Circular photon orbit at 1.5 r_s; rays with impact parameter below (3√3/2) r_s ≈ 2.6 r_s are captured (the visible "shadow"); weak-field deflection is 2r_s/b + (15π/16)(r_s/b)². The innermost stable circular orbit is 3 r_s (0.5c orbital speed there). The disk image is traced per pixel with a symplectic integrator of that equation.

Honest simplifications. Classical general relativity only: no Hawking radiation, no quantum gravity, no rotation (real holes spin), no charge, and the singularity is where the theory stops, not a place we can describe. The shader integrates a fixed number of steps, follows each ray for at most about 2.5 turns (so the thin higher-order photon rings are missing), takes the camera as a static (hovering) observer at the current radius — the falling observer's aberration and Doppler shifts are not applied — and draws a thin flat disk with a made-up texture, Doppler beaming and gravitational redshift only roughly. Inside the horizon a static observer does not exist, so the view stops at 1.02 r_s. The disk, star field and astronaut were baked in Blender 5.2; the astronaut is not to scale.

Numbers: G = 6.6743e-11, c = 299 792 458 m/s, solar mass 1.98847e30 kg.