About Gravity Hands

Gravity Hands is an interactive browser experience that turns your hands into gravity wells. Using your webcam and machine learning-powered hand tracking, particles on screen are attracted to your hands, forming beautiful accretion disk patterns just like those around black holes.

The Inspiration

This project was inspired by a visit to Clark Planetarium in Salt Lake City, Utah. Their Gravity Floor exhibit lets visitors create their own gravity wells by stepping on an interactive floor display. Watching kids (and adults!) have an absolute blast collecting stars and creating orbital patterns gave me an idea: what if I could bring this experience home?

Instead of a floor you step on, Gravity Hands uses your webcam to track your hands in real-time. The result is the same magical feeling of controlling gravity itself, but accessible from any device with a camera.

How It Works

Under the hood, Gravity Hands combines several technologies:

• MediaPipe Hands - Google's machine learning solution for real-time hand tracking
• Three.js - A powerful 3D graphics library for rendering thousands of particles
• Custom Physics Engine - Plummer-softened gravity with zone-based behaviors for realistic accretion disk formation

The physics simulation includes four distinct zones around each gravity well: a far field where particles drift gently, an orbit zone where tangential forces create orbital motion, an accretion disk where particles form stable rings, and a core where particles are captured and respawned.

Privacy First

Your camera feed never leaves your device. All hand tracking happens locally in your browser using WebGL acceleration. No video is ever uploaded, stored, or transmitted anywhere.