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j1-2k8-mtH02: Kepler's Orrery

August 1, 2008

Orrery is a generative music system that uses gravity equations to
"compose" and play music.

Start with planets (or
stars or particles) that each have mass, position, and velocity, then
run a n-body gravity simulator to make them move. They attract each
other, accelerate, swirl around, and slingshot off each
other. Sometimes they collide, and that's what plays the music.

Each body can have a melody attached to it, and plays its next
note when it collides.

Composing for this system is tricky,
but fun. You set up the initial world by specifying where the planets
and the rocks (represented by squares; they have mass and position,
but don't move) are, give them initial velocities, and see how they
move. Then you have to make melodies that work when played randomly
against the other melodies, with no control of when the notes get
played or for how long -- just the order.

Download Audio

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Simran Gleason is the creator of Kepler's Orrery
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