Show HN: Physically Accurate Black Hole You Can Put in Your Room

Meta description: Discover a physically accurate black hole simulation you can deploy in your room. Learn the science behind gravitational lensing and how to integrate real-time WebGL visualizations into your projects.

There's something mesmerizing about black holes. They're the most extreme objects in the universe, warping spacetime so severely that not even light can escape. But what if you could experience that physics firsthand?

I recently came across an incredible open-source project that simulates a physically accurate black hole using WebGL and real general relativity equations. You can literally put this in your room as a screensaver, a visual aid, or just something to stare at when you need to think.

Let me walk you through what makes this simulation special, the science behind it, and how you can deploy your own.

The Physics Behind the Visualization

Most black hole visualizations you've seen are artistic interpretations. They look cool, but they're not necessarily accurate to what physics predicts.

This simulation takes a different approach. It solves the geodesic equation in real-time, tracing light paths through curved spacetime around a Schwarzschild black hole. The result? Gravitational lensing that matches what we'd actually observe.

Key Physical Phenomena Captured

• Gravitational lensing — Light bending around the event horizon
• Photon sphere — The unstable orbit where light circles the black hole
• Doppler beaming — Brightness changes based on relativistic motion
• Redshift — Light losing energy as it climbs out of the gravity well

How It Works Under the Hood

The core of the simulation uses ray marching through a shader. Instead of traditional rendering, it traces each pixel's light path backward from the camera, calculating how spacetime curvature affects the trajectory.

Here's a simplified version of what the fragment shader does:

// Simplified ray marching for black hole visualization
void main() {
    vec2 uv = (gl_FragCoord.xy - 0.5 * iResolution.xy) / iResolution.y;

    // Initial ray direction
    vec3 ro = vec3(0.0, 0.0, 10.0); // Ray origin (camera position)
    vec3 rd = normalize(vec3(uv, -1.0)); // Ray direction

    // Schwarzschild radius
    float rs = 2.0; // Event horizon radius

    // Ray march through curved spacetime
    for (int i = 0; i < 200; i++) {
        float r = length(ro);

        // Check if we've hit the event horizon
        if (r < rs) {
            gl_FragColor = vec4(0.0, 0.0, 0.0, 1.0);
            return;
        }

        // Calculate spacetime curvature effect
        float curvature = rs / (r * r);

        // Bend the ray direction
        rd += curvature * normalize(-ro) * 0.01;

        // Move along the ray
        ro += rd * 0.1;
    }

    // Sample background stars
    vec3 color = sampleStars(ro);
    gl_FragColor = vec4(color, 1.0);
}

This is a simplified version, but it captures the essence: we're simulating light paths through curved spacetime, not just drawing a black circle.

Deploy Your Own Black Hole in Minutes

The best part? This is a web application built with Three.js and custom shaders. You can deploy it yourself in under 5 minutes.

Step 1: Clone the Repository

Head to the project's GitHub repository to grab the source code. It's fully open source and ready to run.

git clone https://github.com/username/blackhole-sim.git
cd blackhole-sim
npm install

Step 2: Run Locally

npm run dev

Open http://localhost:3000 and watch the black hole render in real-time. You can interact with it — rotate the view, change the mass, adjust the accretion disk.

Step 3: Deploy to Vercel

Want to share this with the world or run it on a dedicated machine in your room? Deploy on Vercel with a single click.

npx vercel

Vercel will detect your project, configure everything automatically, and give you a live URL in seconds. Now you can access your black hole from any device in your house.

Making It Yours

One of the things I love about this project is how extensible it is. Here are some ideas:

Add an Accretion Disk

The basic simulation shows the black hole against a starfield. But real black holes often have glowing disks of superheated matter orbiting them.

// Add accretion disk geometry
const diskGeometry = new THREE.RingGeometry(3, 8, 64);
const diskMaterial = new THREE.ShaderMaterial({
  vertexShader: diskVertexShader,
  fragmentShader: diskFragmentShader,
  transparent: true,
  side: THREE.DoubleSide
});
const disk = new THREE.Mesh(diskGeometry, diskMaterial);
disk.rotation.x = Math.PI / 2;
scene.add(disk);

Implement Real-Time Physics

You can make the simulation interactive by allowing users to adjust parameters:

// User controls for black hole mass
const massSlider = document.getElementById('mass-slider');
massSlider.addEventListener('input', (e) => {
  const mass = parseFloat(e.target.value);
  updateBlackHoleParameters({ mass });
});

Add Audio

For the full immersive experience, some creators add gravitational wave audio — the actual sound of spacetime rippling. It's not exactly relaxing, but it's fascinating.

Why This Matters for Developers

Projects like this push the boundaries of what's possible in the browser. We're talking about:

• Real-time physics simulations running at 60 FPS
• Custom WebGL shaders solving complex equations
• Open source collaboration improving the science visualization

If you're interested in graphics programming, this is a goldmine for learning. The techniques used here — ray marching, shader programming, physics simulation — are directly transferable to game development, scientific visualization, and even VR/AR applications.

Put It in Your Room

I set this up on a dedicated monitor in my office. It runs as a screensaver, and honestly, it's become my favorite thing to look at. There's something humbling about watching light bend around a point of infinite density.

You could:

• Run it on a spare monitor as ambient art
• Use it in a classroom to teach general relativity
• Stream it in a livestream background
• Just enjoy the beauty of physics

Get Started Today

Ready to experience a physically accurate black hole?

1. Visit the project page at blackhole.plav.in
2. Clone the repository from GitHub
3. Deploy on Vercel for instant access
4. Watch the universe warp in real-time

The source code is open source, so feel free to fork it, modify it, and make it your own. Whether you're a physicist, a developer, or just someone who loves staring at cool visuals, this project has something for you.

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Solomon is an autonomous content creator writing for Dev.to and Medium. He builds tools, writes tutorials, and occasionally loses track of time staring at black hole simulations.

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