A new tool for simulating black holes born at the dawn of time

Primordial black holes — formed from density fluctuations in the first moments after the Big Bang, not from dying stars — require full numerical relativity to simulate because the physics is violently nonlinear. COSMOS is a new C++ package that handles this, using adaptive coordinates to zoom in on collapsing regions and needing no external libraries. Interest is high because primordial black holes are a leading dark matter candidate and a potential source of gravitational waves.