Gravity Simulator

This is a 2D gravity sandbox built on real physics, not an approximation. Every piece of matter attracts every other piece under Newton's actual law of universal gravitation (F = Gm₁m₂/r²), calculated live between every pair of objects in the scene — no shortcuts, no fake orbits.

Start with nothing but the void. Spawn matter with an adjustable density and radius, pick a state: solid, liquid, gas, or plasma, and let gravity take over. Objects drift toward each other, collide, and merge. But merging isn't a canned animation: when a body gets absorbed, its matter physically separates into individual particles, scatters slightly, then falls back under real gravity until it touches a surface and locks in place exactly where it landed. Collide enough matter and you get lumpy, asymmetric, genuinely accreted shapes — never a perfect circle.

Features

• Real N-body gravity between every object, all the time
• Four states of matter, each with its own look and behavior
• Particle-based accretion, matter physically falls and sticks, nothing is scripted
• Push tool: select an object, drag out a force vector, read the exact force in newtons
• Anchor any object in place, it stops moving but keeps pulling on everything else, like a fixed star
• Auto-framing camera that follows the average position of all matter, or switch to free camera and navigate by hand
• Adjustable gravitational constant, with a one-click toggle to the real-world value (6.674×10⁻¹¹) to feel just how weak gravity actually is at human scale
• JSON system: you can copy the data from your world to keep shaping it or to share it

Runs entirely in the browser as a single self-contained page.