EVENT LOG
REPLAY
buffer 0 frames
Each scenario loads a ready-made system. You can edit anything once it is running.
Everything here also works from the command palette: press / and type what you want.
Version 4 · physics: direct N-body, galactic halos with bar and spiral density waves, post-Newtonian black-hole orbits, Leinhardt & Stewart collision scaling, Roche and tidal heating, Jeans escape.
Speed. The readout says how much simulated time passes per real second. Above ×10⁶ the integrator may not keep up; the SIM-LIMITED chip appears when it slows down.
Collisions. Slow impacts merge; grazing ones can skim past (hit-and-run); fast ones erode or shatter bodies into fragments and debris. Big impacts melt crusts into magma oceans.
Roche limit. Inside it, tides tear bodies apart and fragments can't re-merge, so rings form. Black holes do this to whole stars: a tidal disruption event.
Accretion cross-section. Real planet formation takes millions of years. This slider inflates collision radii so you can watch it in minutes; set it to ×1 for physical behavior.
Black holes. Anything entering the capture zone is swallowed. Infalling gas heats into a glowing accretion disk, and the hole's luminosity tracks how fast it feeds. Close to a black hole a general-relativity correction makes orbits precess.
Galaxies. Each galaxy is a central black hole inside a dark-matter halo that keeps rotation speeds flat. Stars are tracers that orbit in that halo, a rotating bar and spiral density waves. Galaxies feel dynamical friction, so satellites sink and big pairs merge. Cosmic speeds up to 10¹⁶× (317 million years per second) unlock in galaxy scenarios.