Big Bang and Cosmic Expansion (2D)

Radiation era

Presets

Universe parameters (changing restarts)

Playback and view

Auto-fit the growing universe to the screen Distance rings and Hubble sphere

Click a galaxy to make it the observer, then drag the observer ring to move it to another galaxy. Galaxies are coloured by recession velocity (red = receding, blue = approaching). Dashed orange circle: Hubble sphere, where v = c. Drag the background to pan, wheel to zoom. Model: Friedmann equations, H(a)² = H₀²(Ωr a⁻⁴ + Ωm a⁻³ + Ωk a⁻² + ΩΛ).