Big Bang Simulator
Ten animated 3D stages rewind to the hot dense beginning, then ride space's expansion, inflation, the particle soup, recombination, and the first stars into today's accelerating cosmic web.
Big Bang Simulator Knowledge file
The Big Bang describes the universe expanding and cooling from an extremely hot, dense state—not matter exploding into pre-existing space.
At a glance
- Age of the universe
- About 13.8 billion years
- Stages
- 10
- Universe becomes transparent
- About 380,000 years later
- Current state
- Accelerating expansion
Core concepts
Space itself stretches
Distant galaxies generally recede because the scale of space between them grows, not because they fly away from a central point.
The microwave background preserves an early image
When the universe cooled enough for electrons and nuclei to combine, light began traveling freely; today we observe it as the cosmic microwave background.
Tiny fluctuations grew into galaxies
Small early differences in density gradually grew under gravity, forming stars, galaxies, and the cosmic web.
Ways to understand
- Earliest eraInflation and a sea of particles
The universe expanded rapidly and cooled as energy gradually became different fundamental particles.
- After 380,000 yearsAtoms form and the universe becomes transparent
Electrons joined nuclei, light stopped scattering constantly, and the microwave background was released.
- Hundreds of millions of years to todayStars, galaxies, and the cosmic web
Gravity amplified density fluctuations, while dark energy later began driving accelerated expansion.
What to observe
- ObserveConnect time and temperature
In general, the younger universe was hotter and denser, while expansion continually stretched radiation to longer wavelengths.
- ObserveLook for the origin of structure
From an almost uniform particle distribution to a filamentary cosmic web, watch gravity amplify small differences.
- ClarifyThere is no visible explosion center
In a large-scale uniform model, observers anywhere see other distant galaxies generally moving away.