Universe

Circles in a box, and a handful of laws you can rewrite while they run: gravity, every body pulling on every other; a steady pull down, like standing on a planet; like charges pushing apart; wind; drag; and how much a collision gives back.

Press and drag to throw a body; just click to drop one. Pick a universe to start from, then change its laws. Charged bodies with a minus charge are drawn as rings. space play · s step · r reset · c empty · t trails

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Written in Dart, compiled to JavaScript, baked into this page. Circles only, no spin or friction. Energy and momentum in the readout drift only when drag, wind, walls or sticky collisions say they should.