Is this a physically accurate black hole?

It is a stylised accretion flow, not a relativistic simulation. The tangential and inward components follow Keplerian intuition and the horizon is a hard cull radius, but there is no light bending or gravitational redshift. It is built to look right, not to be a research model.

Is the Black Hole Accretion screensaver free?

Yes. It runs free in your browser with nothing to download or install, and it works offline once the page has loaded.

What does the Seed setting do?

Everything is deterministic from the seed: the noise table, where the field’s features land and the order particles spawn in. Leave it blank for a fresh random layout on every run, or type any short word or number to get the same layout back each time.

Why does the image ripple when I move the mouse?

The cursor and a lagging echo of it act as two wave sources. Their interference pattern nudges nearby particles onto the bright fringes and dims the dark ones, so the flow visibly reacts to you. Turn off Cursor ripples in the settings if you want the field left alone.

How do I exit the Black Hole Accretion screensaver?

Press the ESC key at any time to leave fullscreen and return to the page.

Why is the disc brighter near the centre?

Gas orbits faster and is hotter there, so the inner region radiates the most energy before the gas crosses the event horizon.

Can anything escape once it passes the horizon?

According to general relativity, not even light. The event horizon marks the boundary beyond which no signal can reach the outside.

Is the disc the same thing as the black hole?

No. The hole is the region inside the horizon, and the disc is surrounding gas that is heated as it falls inward.

Black Hole Accretion Screensaver

Black Hole Accretion is a free, in-browser screensaver where thousands of particles spiral into a black hole. The flow combines Keplerian tangential motion with an inward drift that steepens close to the horizon, so matter orbits and spirals rather than plunging straight in, speeding up and brightening as it goes. Anything that crosses the horizon is consumed, which is what keeps the centre a clean dark void instead of a bright pile-up. Nothing to download, and ESC exits at any time.

How the Black Hole Accretion screensaver works

At every point the field has two parts. A tangential component circulates around the hole in a seeded direction — the frame-dragging spin. A radial component points inward and grows stronger as one over the distance to the horizon, so far out the flow is nearly circular and close in it is nearly a plunge. The sum is a spiral.

The speed is not constant. It rises as the particle approaches, capped at a few times the free-stream value, so the innermost ring moves fastest and, with additive strokes, glows brightest. That rising speed near the horizon is most of the visual drama and mirrors how a real accretion disc is hottest at its inner edge.

A particle that crosses the event horizon radius is removed and respawned elsewhere. Without that cull, particles would stack up at the centre and paint it white; with it, the hole stays black and the disc keeps its sharp inner edge.

The hole’s position and spin come from the seed. The field itself is fixed, so Evolve acts only through a blended noise field — and blending Domain warp in at around 45% gives the studio’s Warped horizon look, where the infalling streams fold and marble on the way in.

Accretion discs and why the inner edge glows

Matter falling toward a black hole rarely drops straight in. It carries angular momentum, so it settles into a flattened accretion disc and spirals inward, losing that momentum gradually through turbulence and magnetic effects. Friction in the turbulent gas heats it, which is why accreting black holes are among the brightest sources in the universe, even though the hole itself emits no light.

The region closest to the hole is both the fastest and the hottest. Orbital speed climbs as radius shrinks, and in a thin disc the temperature rises steeply inward, hot enough to emit X-rays just outside the event horizon. General relativity also adds a limit called the innermost stable circular orbit, inside which material can no longer circle and instead plunges. Frame dragging, predicted for a rotating hole, means space itself is twisted along with the spin, so infalling matter is pulled into the same sense of rotation.

This display is a stylised sketch of that idea rather than a simulation. A faithful treatment would require general relativistic ray tracing, gravitational lensing and the bending of light around the hole, which produces the bright, curved halo seen in images of real discs. Treat the picture as a visual metaphor for infall and heating, not as a measurement.

A worked example

At the defaults — Ultraviolet palette, 2600 particles, Trail 62 — violet and cyan streams circle a dark disc, tighten into a bright ring just outside it, and disappear. Set Trail to 90 and the spiral arms become dense and continuous like a photograph of a galaxy; raise Speed to 2 and the inner ring becomes a blur of light.

Settings & tips

Blend Domain warp at 45% for marbled, folded infall; blend Vortices at 30% for a turbulent disc.
Ember makes the disc look like glowing plasma; Cyanotype turns it into a radio-telescope image.
Reseed to move the hole and flip its spin direction.

Frequently asked questions

Is this a physically accurate black hole?: It is a stylised accretion flow, not a relativistic simulation. The tangential and inward components follow Keplerian intuition and the horizon is a hard cull radius, but there is no light bending or gravitational redshift. It is built to look right, not to be a research model.
Is the Black Hole Accretion screensaver free?: Yes. It runs free in your browser with nothing to download or install, and it works offline once the page has loaded.
What does the Seed setting do?: Everything is deterministic from the seed: the noise table, where the field’s features land and the order particles spawn in. Leave it blank for a fresh random layout on every run, or type any short word or number to get the same layout back each time.
Why does the image ripple when I move the mouse?: The cursor and a lagging echo of it act as two wave sources. Their interference pattern nudges nearby particles onto the bright fringes and dims the dark ones, so the flow visibly reacts to you. Turn off Cursor ripples in the settings if you want the field left alone.
How do I exit the Black Hole Accretion screensaver?: Press the ESC key at any time to leave fullscreen and return to the page.
Why is the disc brighter near the centre?: Gas orbits faster and is hotter there, so the inner region radiates the most energy before the gas crosses the event horizon.
Can anything escape once it passes the horizon?: According to general relativity, not even light. The event horizon marks the boundary beyond which no signal can reach the outside.
Is the disc the same thing as the black hole?: No. The hole is the region inside the horizon, and the disc is surrounding gas that is heated as it falls inward.

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