Big Bang & Cosmic Expansion Simulator

This simulator integrates the Friedmann equation of the standard Λ-CDM cosmological model to grow a field of galaxies from a hot, dense early state into a large-scale structure. Each galaxy keeps a fixed comoving coordinate; only the scale factor a(t) changes, stretching the whole field outward at once — the same mechanism behind cosmological redshift and the Hubble law. Adjust the matter density and Hubble constant to see how a matter-dominated universe decelerates while a dark-energy-dominated one accelerates, and watch the camera pull back automatically to keep the expanding field in view.