Real physics, playable speed
Barnes–Hut gravity, symplectic integrators, and GPU compute keep a living universe honest — and fast enough to wander.
A grand stellar simulation · from Starhearth
From quarks to the cosmic web.
Every atom remembers.
Cosmogony is a universe biography you can stand inside: real gravity, honest time, and matter that carries its whole history — from the first light to the long dark.
rust · bevy · wgpu compute · 1.5M splats, simulated and drawn from one buffer
The premise
A biography of a universe.
Begin at the beginning — a hot, smooth, expanding everything — and watch structure emerge on its own: the web, the galaxies, the stars, the slow chemistry of worlds.
There is no avatar and no rewind. You are a presence, not a character. Time only flows forward, and everything that happens, happened.
star #4d3f92a1 · G2 V · main sequence ├ mass 1.02 M☉ · age 4.6 Gyr ├ [Fe/H] −0.03 · [α/Fe] +0.01 ├ iron 65% type Ia · 35% core-collapse ├ worlds 7 · temperate 1 · moons 14 └ frost line 2.7 AU
observation log · derived on demand, nothing stored
Four laws of the build
Grand first. Honest always.
Every atom remembers
Focus any star and the record derives itself from its id: mass, phase, worlds — and where its metals came from, down to the split between type Ia and core-collapse iron.
No avatar. No rewind.
You are a presence, not a hero. The universe doesn’t orbit you, and time never runs backward.
The dark sector
Most of everything is invisible. Dark matter scaffolds the web; dark energy stretches it. You’ll feel both long before you see either.
Field report
Now forming: the first galaxies.
- now
Continuous zoom from a spiral galaxy of 1.5M splats down to a cratered moon: true Kepler orbits, binaries and multiples, volumetric nebulae that live and die on the sim clock, and supernovae you can witness in the disk.
- colour
Nothing is art-directed by hand. A star's colour comes from its blackbody temperature, its metallicity, its TiO bands; a world's comes from what condensed out of its disk. Physics picks the palette.
- honest
The simulation runs headless and deterministic — same seed, same universe, forever — with 127 physics tests holding it to account.
- next
Instruments to look with, the Chronicle that remembers what you saw, and the grain of a printed star atlas — quantized through ramps authored in Sprael.