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Expanding Universe: Scale Factor & Hubble's Law (2D)

A 2D top-down companion to the 3D balloon-analogy Big Bang simulator: a comoving grid of galaxies expands under a real Friedmann scale factor a(t), with live Hubble's-law readouts (v = H(t)·d) as you drag the Hubble constant and time-since-Big-Bang sliders.

Cosmology2DModerate60 FPS📱 Mobile-adapted⇄ 3D version

A flat 2D companion to the 3D balloon-analogy Big Bang simulator: a grid of galaxies at fixed comoving positions is stretched apart by a real matter-dominated scale factor a(t) = (t/t₀)^(2/3), with t₀ = 2/(3H₀) tying the Hubble constant directly to the universe's age. Drag the H₀ and time-since-Big-Bang sliders, or press play to watch the expansion unfold, and click any two galaxies to measure their proper distance and recession velocity via Hubble's law v = H(t)·d.

⚙ Under the hood

A flat top-down 2D companion to the 3D balloon-analogy Big Bang simulator: a grid of galaxies at fixed comoving positions is stretched apart by a real matter-dominated scale factor a(t), with adjustable Hubble constant and time-since-Big-Bang sliders and click-to-measure Hubble's-law distance/velocity readouts.

cosmologybig banghubble's lawscale factorexpanding universefriedmann equation2D

2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install