Is this black hole simulator free?

Yes. It runs free in your web browser on WebGL 2, with no install, no account and no ads. On a slower device it renders at a lower resolution to keep the motion smooth.

Is it a real simulation or a video?

It is computed live. For every pixel the path of light is traced through the gravity of a non-spinning (Schwarzschild) black hole, which bends the disk into an arc and draws the photon ring. The disk's brightness includes Doppler beaming and gravitational redshift.

What is the photon ring?

The thin bright ring at the edge of the shadow. It is light that circled the black hole, once or more, before escaping toward you.

Where can I see more black holes?

The Everdust app has more black hole worlds and games, such as Black Hole Golf. It is free on the App Store for iPhone, iPad and Apple Vision Pro, on Google Play for Android and on the Meta Horizon Store for Meta Quest. You can also play Black Hole Golf free in your browser on this site.

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Black Hole

Black hole simulator

A black hole's shadow wrapped in a glowing accretion disc, with the far side of the disc bent up over the top by gravity and a thin photon ring at the edge of the shadow.

Drag to turn it, pinch or scroll to zoom, double-tap to reset.

The idea: Gravity bends light around the hole, so you see the back of the disc as an arc over the shadow. This web version traces the bent path of light for every pixel around a non-spinning black hole, with the side of the disc moving toward you beamed brighter.
With music: Bass swells the disc and its brightness; kicks send rings travelling out through it; treble flares the inner edge and twinkles the stars. Tap Demo beat for our own beat, or Your music to let it hear the room.
How it runs: It’s the same live simulation as in the Everdust apps, running in your browser on WebGL 2. If your device struggles, it lowers the detail a step at a time to keep the motion smooth.

Why does a black hole bend light?

A black hole is so much mass packed into so little space that nothing, not even light, can climb back out once it crosses the boundary called the event horizon. Outside that boundary light can still escape, but gravity bends its path, as Einstein's general relativity predicted in 1915.

That bending is why a black hole wrapped in a disk of hot gas looks so strange. Light from the far side of the disk, which should be hidden behind the hole, is bent up and over the top, so the back of the disk shows as an arc above the dark shadow. Closer in, some light loops around the hole before it escapes and forms a thin, bright ring at the edge of the shadow: the photon ring.

The disk is lopsided too. Gas orbiting toward you looks brighter because of its speed, an effect called relativistic beaming, and the side moving away looks dimmer and redder.

In 2019 the Event Horizon Telescope released the first image of a black hole's shadow, in the galaxy M87, and in 2022 an image of Sagittarius A*, the black hole at the center of our Milky Way.

Here the path of light is traced for every pixel around a non-spinning black hole. Real black holes spin, which shifts and flattens the shadow a little.

Questions

Is this black hole simulator free?: Yes. It runs free in your web browser on WebGL 2, with no install, no account and no ads. On a slower device it renders at a lower resolution to keep the motion smooth.
Is it a real simulation or a video?: It is computed live. For every pixel the path of light is traced through the gravity of a non-spinning (Schwarzschild) black hole, which bends the disk into an arc and draws the photon ring. The disk's brightness includes Doppler beaming and gravitational redshift.
What is the photon ring?: The thin bright ring at the edge of the shadow. It is light that circled the black hole, once or more, before escaping toward you.
Where can I see more black holes?: The Everdust app has more black hole worlds and games, such as Black Hole Golf. It is free on the App Store for iPhone, iPad and Apple Vision Pro, on Google Play for Android and on the Meta Horizon Store for Meta Quest. You can also play Black Hole Golf free in your browser on this site.

This is one world, in your browser

The full version is in the Everdust app.

The app has many more live worlds at full detail, games built on the same physics and narrated stories you step inside. It’s free to download, with no ads, on the App Store for iPhone, iPad, Apple Vision Pro and Apple TV, on Google Play for Android phones and tablets, on the Meta Horizon Store for Meta Quest and from everdust.ai for Mac.